Me = 9.8 (6.4 x 106)2/6.67 x 10-11
or
 Chapter:9MACHINES | | Define the following terms: | | MACHINE |
| A machine is a device by means of which work can be performed easily or in a convenient manner.
A machine can be used :
 To lift heavy loads by applying little force.
To enlarge magnitude of force
To increase rate of work done
To change the direction of force
Example of simple machines are : Lever, pulley, inclined plane, wedge, screw etc. | EFFORT OR POWER |
| | The power directly applied to a machine to lift a load is called Effort or Power. It is denoted by ‘P’. | LOAD OR WEIGHT |
| | The weight lifted by a machine is called Load. It is denoted by ‘W’. | MECHANICAL ADVANTAGE |
| The ratio of weight (load) lifted by a machine to the force(effort) applied on a machine is called mechanical advantage of the machine.
Greater the value of mechanical advantage of a machine, more easier is the work done.
Mathematically, | M.A = load/effort | | OR | M.A = W/P | | UNIT: | | It has no unit. | INPUT |
| | Amount of work done on a machine by a given effort (force) is called input of a machine. | Input = effort x distance through which effort acts
OR | input = P x d | OUTPUT |
| | Amount of work done by a machine on the load (weight) is called output of the machine. | Output = load x distance covered by the load
OR | Output = W x D | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | EFFICIENCY |
| | The ratio of output of a machine to the input of machine is called its efficiency. | h = output/input
h = (W x D)/(P x d)
Efficiency in %:
h = (W x D)/(P x d )x100 | | UNIT: | | It has no unit. | IDEAL MACHINE |
| An ideal machine is a hypothetical machine whose output is equal to its input.
For an ideal machine | output = input | | Efficiency of an ideal machine is 100% because there is no loss of energy in an ideal machine due to friction or any other means that can waste useful energy. | | M.A of an ideal machine is d / h. | LEVER |
| Lever is a simple machine which is used to lift heavy bodies or heavy load in a very easy way.
Lever consists of a rigid bar capable to rotate about a fixed axis called fulcrum. Effort is applied at one end of the bar and weight can be lifted from the other end. | | TYPES OF LEVER |
| | There are three kinds of lever depending upon the positions of load , effort and fulcrum. | FIRST KIND OF LEVER |
| | In the first kind of lever, the fulcrum F lies between effort (P) and load (W). | | | Example: common balance, seesaw, scissors, handle of hand pump. | SECOND KIND OF LEVER |
| | In the second kind of lever, load (W) lies between effort (P) and fulcrum (F). | | | Example: door, nutcracker, punching machine. | THIRD KIND OF LEVER |
| In the third kind of lever, effort (P) lies between load (W) and fulcrum (F).
Example: forceps, jaws, human forearm, firetong. | |
Chapter:10MATTER | | | | KINETIC MOLECULAR THEORY OF MATTER |
| | According to kinetic theory of matter: | - Matter is made of very small particles called MOLECULES.
- These molecules are in a state of motion.
- They possess Kinetic Energy.
- Molecular motion may be translational , rotational or vibrational.
- These molecules attract each other.
- As the temperature of a substance is increased , its molecular speed is also increased and vice versa.
- If a substance is compressed , The K.E of its molecules increases and its temperature rises
For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | BROWNIAN MOTION |
| | A famous scientist ROBERT BROWN observed that molecules of a substance are moved in ZIG ZAG path. Their motion is random. They collide with each other and move in a new direction after collision in ZIG ZAG fashion. This type of motion present in the molecules of matter is called "Brownian motion". | Brownian motion | ELASTICITY |
| | The property of solid by virtue of which a solid body recovers its original shape after the removal of an applied force is called "ELASTICITY". | ELASTIC LIMIT |
| If applied force on a solid is gradually increased, a state is reached after which the material will not return to it original shape even after the removal of applied force. This limit is called "ELASTIC LIMIT".
After elastic limit, material is permanently deformed. Different substances have different elastic limit. | STRESS |
| When a body is deformed, the internal force came into play per unit area to restore it to its original state is called "STRESS"
OR
"Stress is an opposing force expressed per unit area which resists any change in shape." | Stress is equal to the force per unit area.
Mathematically: | 
or
 | | Stress produces when a body is made to change in length, volume or Shape by the application of an external force. |
Chapter:11THERMAL CONDUCTIVITY | | | Thermal conductivity is defined as" the amount of heat conducted in one second through one cubic meter of a substance whose two opposite faces are maintained at the temperature difference of one degree centigrade."
It is denoted by "K".
Formula
K=QL/ADTt
Unit :
Unit of thermal conductivity is J/mKs OR watt/m.K. | EXPRESSION FOR
THERMAL CONDUCTIVITY | | Experiments indicates that the amount of heat conducted through a solid block is :
Directly proportional to temperature difference between two faces of block. | DQ a DT ...................... (i) | | Directly proportional to the area of cross - section of block. | DQ a A ...................... (ii) | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | | Directly proportional to the the time interval to which heat is conducted. | DQ a t ...................... (iii) | | Inversly proportional to the length of block. | DQ a 1/L ...................... (iv) | | Combining above facts,we get | DQ a DT.A.t /L | | OR | | | OR | |
Chapter:12WAVES AND SOUND | | Define the following terms: |
| PERIODIC MOTION | | | A motion that repeats itself in equal intervals of time is called Periodic Motion. | VIBRATORY MOTION | | | If a particle in periodic motion moves back and forth (To and Fro) over the same path, then this type of motion is called Vibratory or Oscillatory Motion. | VIBRATION | | A complete round trip of a vibrating body is called a Vibration.
or
The motion of a vibrating body from one extreme point to the other
extreme point and back to the first extreme point is called VIBRATION. | | For Example the motion of the bob of Simple Pendulum from A to B & back from B to A via point "O" is called one Vibration. | |
| TIME PERIOD | | | Time required to complete one vibration is called Time Period of vibrating body. It is denoted by "T". | FREQUENCY | | Number of vibrations executed by a vibrating body in one second is called its frequency.
It is denoted by "f".
Frequency is reciprocal of time period f = 1/T
Unit of frequency : Hertz
Other units : cycle/sec or vibration/sec. | DISPLACEMENT | | Displacement of the vibrating body at any instant in its distance from the mean
position at that instant either right or left side. Here it is denoted by "x". | AMPLITUDE | | Maximum displacement of a vibrating body on either side of its
equilibrium position is called amplitude of vibration. It is denoted by  . | SIMPLE HERMONIC MOTION | | "Type of vibratory motion in which acceleration of body is directly proportional its displacement and the
acceleration is always directed towards the equilibrium (mean) position is called Simple Harmonic Motion. " | acceleration a - displacement | a a - x | | Negative sign indicates that acceleration and displacement are opposite in direction. | | Examples of S.H.M : | | Motion of the bob of a simple pendulum, spring-mass system, guitar wires, prongs of a tuning fork |
Chapter:13REFLECTION OF LIGHT | | REFLECTION OF LIGHT |
| | When light rays traveling is a medium reaches the boundary of other medium, they turn back to the first medium. This phenomenon of turning back of light into the same medium after striking the boundary of other medium is called Reflection of Light. | | LAWS OF REFLECTION |
| 1. The angle of incident is equal to the angle of reflection i.e. <i = <r
2. The incident ray, the reflected ray and the normal lie on the same plane. | | REGULAR REFLECTION | | | When a beam pass of parallel light rays is incident on a smooth and plane surface, the reflected rays will also be parallel. This type of reflection is called Regular Reflection. | | IRREGULAR REFLECTION | | | When a beam of parallel light rays is scattered in all directions. Therefore the parallel rays incident on the surface will reflect in different directions. This type of reflection is called "Irregular or Diffuse Reflection". | | CENTER OF CURVATURE | | | Center of curvature of a lens or mirror is defined as the center of the sphere of which the less or mirror is a part. C = Center of curvature. | | RADIUS OF CURVATURE |
| Radius of curvature is the radius of sphere of which the lens or mirror is a part.
| PC = Radius of curvature
OR
PC = R | | POLE | | | For latest information , free computer courses and high impact notes visit www.citycollegiate.com | | | The middle or center point of a lens or a mirror is called "Pole" P = Pole. | PRINCIPLE AXIS |
| | The straight line joining the center of curvature to the pole is called Principle Axis. . | | PRINCIPLE FOCUS | | When a narrow beam of light, parallel to the principle axis and closed to it, is incident on the surface of a mirror or lens, the beam reflected or refracted is converged at a fixed point on the axis. This point is called Principle Axis.
F = principle focus. | | FOCAL LENGTH | | | The distance between the pole of a lens or mirror to the principal focus is called Focal Length (PF) of lens or mirror. Focal length is always equal to half of the radius of curvature of lens or mirror. f = R/2. | | | Write down the characteristics of image formed by a plane mirror | 1. Image formed by plane mirror is laterally inverted. This means that right side of the object appears on the left side.
2. Size of image formed by plane mirror is the same as that of size of object.
3. The image formed by plane mirror is virtual because it can not be obtained on the screen.
4. The image is as far behind the mirror as the object is in front of the mirror. Fig. | DEFINE SPHERICAL MIRROR
AND IT'S TWO TYPES | | SPHERICAL MIRROR |
| | Mirror obtained from a spherical surface is known as Spherical Mirror. A spherical mirror is considered as a section of hollow sphere. | | TYPES OF SPHERICAL MIRRORS | | There are two types of spherical mirrors.
1. Concave mirror.
2. Convex mirror. | CONCAVE MIRROR | | | If the inner side of the surface of a spherical mirror is polished to reflect light, the mirror is called a Concave Mirror. Concave mirror converges parallel beam of light. | | CONVEX MIRROR | | | If the outer side of the surface of a spherical mirror is polished to reflect light the mirror is called a Convex Mirror. Convex mirror diverges parallel beam light. | | MAGNIFICATION |
| | Magnification of a mirror or lens is defined as the ratio of the size of image to the size of object. | M = height of image/height of object
M = hi/ho
or
M = q/P | REFRACTIVE INDEX | | | Refractive index is defined as the ratio of sine of the angle of incidence of the sine of the angle of refraction. FORMULA : | m= sine< i/ sine< r | note :Refractive index depends upon the nature of material.
It has no unit. | ANGLE OF DEVIATION | | The angle at which the light ray is refracted (bend) in a prism is called angle of deviation. It is denoted by < D. Minimum value of angle of deviation is called angle of minimum deviation. It is denoted by
<Dm. |
Chapter:14SNELL’S LAW | | | According to Snell’s law | "The ratio of the sine of the angle of incidence to the sine of the angle of refraction is always constant. " | | Mathematically, | Sine <i/sine <r = constant
or
sin< i/sine< r = m | | where m = Refractive index of the material of medium. | TOTAL INTERNAL REFLECTION |
| | When light rays enter from one medium to the other, they are refracted. If we increase the angle of incidence, angle of refraction will also increase. At certain angle of incidence light rays are reflected back to the first medium instead of refraction. This condition or phenomenon is called Total Internal Reflection. |
|
| CRITICAL ANGLE | | | The angle of incidence at which the angle of refraction will become 90o is called Critical Angle. If angle of incidence further increased then instead of refraction, reflection will take place. | DEFECTS OF VISION
Write down the defects of the vision. | There are four common defects of vision:
1. SHORT SIGHTEDNESS OR MYOPIA
2. LONG SIGHTEDNESS OR HYPER METROPIA
3. ASTIGMATISM
4. PRESBYOPIA | SHORT SIGHTEDNESS
OR MYOPIA | SYMPTOMS | | | In Myopia, a person can not see distant objects clearly, but he can see clearly the objects near to him. | REASON | | | The reason for Myopia is either the focal length of lens of eye is too short or the eyeball is very much elongated. | WHAT HAPPENS IN MYOPIA | | | In Myopia, light rays from a distant object are focused in front of the Retina. | | CORRECTION OF DEFECT | | | This defect can be corrected by using a concave lens of suitable focal length | |
ASTIGMATISM |
| | | | If the cornea or the surface of eye is not perfectly spherical. In this situation the eye has different focal points in different planes and an object is not focused clearly on the retina. | CORRECTION OF DEFECT | | | ASTIGMATISM is corrected by using asymmetrical lenses which have different radii of curvature in different planes | PRESBYOPIA
or
lack of accommodating | | | At old age, the eye lens loses its natural elasticity and ability to change its shape and the ciliary muscles weaken resulting in a lack of accommodation. This type of long sightedness is called "PRESBYOPIA". | | CORRECTION OF DEFECT | | | This defect can be corrected by using convex lens for long sighted person and concave lens for short sighted person. | |
LONG SIGHTEDNESS
OR
HYPER METROPIA | | SYMPTOMS | | | In HYPER METROPIA, a person can not see objects clearly which are near to him, but he can see clearly distant objects | REASON | | | The reason for HYPER METROPIA is that either the focal length of the lens of eye is too long or the eyeball is too short. | WHAT HAPPENS IN
HYPER METROPIA | | | In HYPER METROPIA, light rays from a near object are focused behind the Retina. | | CORRECTION OF DEFECT | | | This defect can be corrected by using a convex lens of suitable focal length | | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | POWER OF LENS |
| | Power of lens is defined as the reciprocal of the focal length of the lens in meters. | | FORMULA: | Power = 1/f(in meter) | | Unit of power of lens is Dioptre. | DIOPTRE | | | Dioptre is defined as the power of lens whose focal length is one meter | | if f =1 meter then the power of the lens = 1 dioptre. |
Image Formation by convex lens | | |
| |
|
| POSITION OF OBJECT
When the object is placed at infinity
NATURE AND POSITION OF IMAGE
1. The image will form at the principal focus (F).
2. The image will be real and inverted.
3. The image will be very small in size. |
| | | POSITION OF OBJECT
When the object is placed beyond 2F
NATURE AND POSITION OF IMAGE
1. The image will form between F and 2F.
2. The image will be real and inverted.
3. The image will be smaller in size. | | | | POSITION OF OBJECT
When the object is placed at 2F
NATURE AND POSITION OF IMAGE
1. The image will form at 2F.
2. The image will be real and inverted.
3. The image will be equal in the size of object. | | |
| POSITION OF OBJECT
When the object is placed between F and 2F
NATURE AND POSITION OF IMAGE
1. The image will form beyond 2F.
2. The image will be real and inverted.
3. The image will be magnified. |
| |
| POSITION OF OBJECT
When the object is placed at F
NATURE AND POSITION OF IMAGE
1. The image will form at infinity.
2. The image will be real and inverted.
3. The image will be highly magnified. |
| |
| POSITION OF OBJECT
When the object is placed between the pole (P) and F
NATURE AND POSITION OF IMAGE
1. The image will form on the same side of object.
2. The image will be virtual and erect.
3. The image will be magnified. |
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ASTRONOMICAL TELESCOPE | | | | Introduction |
| | It is an optical instrument used to view heavenly bodies such as moon,stars, planets and distant object. | Construction |
| Astronomical telescope consists of two convex lenses:
 Objective
Eye piece | Objective |
| | The objective is a convex lens of large focal length and large aperture. It usually made of two convex lenses in contact with each other to reduce the chromatic and spherical aberrations. | Eye piece |
| | The eye piece is also a convex lens .Its focal length is smaller than that of objective. It is also a combination of two lenses. | | The objective is mounted on a wide metallic tube while the eye piece is mounted on a small tube .The distance b/w the eye piece and the objective can be changed by moving tubes. | | WORKING | | | The rays coming from a distant object falls on objective as parallel beam at some angle say "a" and these rays after refraction and passing through the objective converge at its focus and make an inverted & real image AB. This image acts as an object for the eye piece. The distance of the eye piece is so adjusted that the image AB lies within the focal length of the eye piece. The eye piece forms the final image .The final image is magnified ,virtual and inverted with respect to object. The final image is formed at infinity. | | MAGNIFYING POWER |
| | The magnifying power (M) of astronomical telescope is given by: | | It is because the object is at infinite distance and hence the angle subtended by the object at eye may be taken as the angle subtended by the object at objective. | M = b/a ............(1) | | since a and b are small angles, therefore we can take: | a = tan a...................
and.....................
b = tan b............. |  ................ | | In right angled triangles DAOB & DAEB |
................... | | This expression shows that in order to obtain high magnification, focal length of object must be large and that of eye piece is small. | LENGTH OF TELESCOPE |
| The distance b/w objective lens and the eye piece is equal to the length of the telescope.
From figure:
OE = length of telescope =L | But
OE = OB + BE | OB = Fo & BE = Fe | | OR | | | OR | L = focal length of objective + focal length of eye piece | COMPOUND MICROSCOPE | | | | | Compound microscope is an optical instrument which is used to obtain high magnification. | Construction |
| It consists of two converging lenses
Objective
Eye piece | Objective | | | The lens in front of object is called objective. Its focal length f1= fo is taken to be very small .The objective forms a real, inverted, and magnified image of the object placed just beyond the focus of objective. | Eye piece |
| | The lens towards the observer's eye is called piece .Focal length of eye piece is greater than the focal length of objective. Eye piece works as a magnifying glass. | Working |
| The objective is so adjusted that the object is very closed to its focus. The objective forms a real,
inverted and magnified image of the abject beyond 2fo on the right hand side. The eye piece is so adjusted that it forms a virtual image at the least distance of distinct vision "d" .The final image is
highly magnified. | | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | Magnifying power |
| In order to determine the magnifying power of a compound microscope ,we consider an object oo' placed in front of objective at a distance p1. Objective forms an inverted image II' at a distance of q1 from objective.
Magnification produced by the objective is given by: | Mo= size of image / size of object | Mo= q1/ p1--------------- (1) | | Eye piece works as a magnifying glass. It further magnifies the first image formed by objective. | | Magnification produced by the eye piece is given by: | Me= size of image / size of object | Me= q2/ p2 | | We know that the eye piece behaves as a magnifying glass therefore the final image will be formed at least distance of distinct vision i.e at 25 cm from the eye. Hence q2 = d | Me= d / p2--------------- (2) | | Using thin lens formula for eye piece : | | 1/f2 = 1/q2 + 1/p2 | | Here f2 = fe, q2 = - d and p = p2 | 1/fe = 1/-d + 1/p2
1/fe = -1/d + 1/p2
Multiplying both sides by "d"
d/fe = -d/d + d/p2
d/fe = -1 + d/p2
1 + d/fe = d/p2
d/p2 = 1 + d/fe----------------(3)
Comparing equation (2) and (3)
Me = 1 + d/fe--------(4) | Total magnification is equal to the product of the magnification produced by the objective and the eye piece.
| M =Mo X Me
M = (q1/p1)(1 + d/fe) | In order to get maximum magnification, we must decrease p1 and increase q1 .Thus maximum possible
value of p1 is fo i.e p = fo and maximum possible value of q1 is the length of microscope i.e q1 = L
Therefore the magnification produced by a compound d microscope is given by: | M = (L/fO)(1 + d/fe) |
Chapter:15NATURE OF LIGHT | | | | Newton’s corpuscular theory of light | | Newton’s corpuscular theory of light is based on the following points
1. Light consists of very tiny particles known as “corpuscular”.
2. These corpuscles on emission from the source of light travel in straight line with high velocity
3. When these particles enter the eyes, they produce image of the object or sensation of vision.
4. Corpuscles of different colours have different sizes. | Huygen’s wave theory of light | | In 1679, Christian Huygens proposed the wave theory of light.
According to huygen’s wave theory:
1. Each point in a source of light sends out waves in all directions in hypothetical medium called "ETHER".
2. Light is a form of energy
3. Light travels in the form of waves.
4. A medium is necessary for the propagation of waves & the whole space is filled with an imaginary medium called Ether
5. Light waves have very short wave length | Quantum theory of light | |
| Quantum theory was put forward by MAX-PLANCK in 1905.
According to quantum theory
“Energy radiated or absorbed can not have any fractional value. This energy must be an integral multiple of a fixed quantity of energy. This quantity is called “QUANTUM”
OR
Energy released or absorbed is always in the form of packets of energy or bundles of energy. These packets of energy are known as QUANTA or PHOTONS |
Chapter:16DEFINITIONS | | | | COULOMB | | | It is SI unit of electric charge. One coulomb (1C) of charge being that quantity of charge which when placed one meter from an identical charge in vacuums repels it with a force of 8.99 x 109 N. | INSULATORS | | Insulators are those materials, which do not allow electric charges to pass through them. In other words, insulators are materials that do not allow electrical current to pass. In insulators electrons are tightly bounded to their atoms. Insulators do not have free electrons.
Examples Plastic, rubber, wood, glass etc. | CONDUCTOR | | Conductors are those materials, which allow electric charges to pass through them. In other words, conductors are materials that allow electric current to pass. In conductors electrons are loosely bounded to atoms. Conductors have free electrons.
Examples:
Copper, Gold, Aluminum, Silver etc. | ELECTRIC FIELD | | | Space or region surrounding a charge or charged body within which another charge experiences some electrostatic force of attraction or repulsion when placed at a point is called Electric Field. | | ELECTRIC INTENSITY | | It is the strength of electric field at a point. Electric intensity at a point is defined as the force experienced per unit positive charge at a point placed in the electric field.
Mathematically, | E=F/q | It is a vector quantity. It has the same direction as that of force. | Units
N/C or Volt/m | E=1/4pe x q/r2 | ELECTRICAL POTENTIAL | | | Electric potential at a point is defined as the amount of work done in moving unit positive charge against the direction of electric field from a point to that point. |
Electrical potential = work done/charge
or
U=work/q
| unit of electric potential in SI system is Volt .
1 volt = 1 Joule/coulomb | VOLT | | Unit of electric potential and potential difference in SI system is called Volt.
| It is defined as
"in an electric field potential b/w two points is 1 volt if the amount of work
done in moving 1 Coulomb charge from one point to another point is 1 Joule." | POTENTIAL DIFFERENCE | | | Potential difference b/w two points A and B is equal to the amount of work done by moving a unit positive charge from point A to point B against the electric field | VB-VA=VAB
or
VAB= (work)AB/q | Unit
Volt or Joule/Coulomb | ELECTRIC CURRENT | | The rate of flow of electric charge through a cross section of a conductor is called Electric Current or Electric charge passes through a cross section of a conductor is called Electric Current.
It is denoted by I. | FORMULA | | I = Q/t | UNITS | | | Ampere in SI system. | OTHER UNITS | | mA (milli Ampere) = 10-3A
m A (micro Ampere) = 10-6A | AMPERE | | | If one coulomb of electric charge passes through a cross section of a conductor in one second, the amount of current passes through it is called Ampere. 1A = 1c/1sec. | RESISTANCE | | | opposition offered by the atoms of a conductor in the flow of electric current is called Resistance. It is a hurdle in the flow of electric current. Different substances have different resistance. Resistance of a conductor increases with the increase in temperature. | SYMBOL | | | It is denoted by R. | UNIT | | | Ohm | |
CAPACITOR | | | | | Capacitor is an electronic device, which is used to store electric charge or electrical energy. A capacitor stores electric charge on its plates. There are a number of types of capacitors available. | STRUCTURE OF CAPACITOR | | | A capacitor consists of two identical conducting plates which are placed in front of each other. One plate of capacitor is connected to the positive terminal of power supply and the other plate is connected to negative terminal. The plate, which is connected to positive terminal acquired positive charge, and the other plate connected to negative terminal. Separation between the plates in very small. The space between the plates is field with air or any suitable dielectric material | 
A parallel plate capacitor | PRINCIPLE OF CAPACITOR | | | Electric charge stored between the plates of a capacitor is directly proportional to the potential difference between the plates. | | Let the potential difference between the plates is V and the charge stored on any one of the plates of capacitor is Q then, | Q a V
Q = CV | where
C= Capacitance of the capacitor | | | CAPACITANCE | | Charge storing capability of a capacitor is called capacitance of capacitor.
Definition: Capacitance of a capacitor is defined as the ratio of the charge stored on any of the plates of capacitor to the potential between the plates. |
COMBINATION OF RESISTORS |
| | . | Resistance can be joined to each other by two ways:
1. Series combination
2. Parallel combination | SERIES COMBINATION | | | Characteristics: | 1. If different resistances are joined with each other such that there is only one path for the flow of electric current then the combination of such resistances is called Series Combination.
2. In series combination current through each resistor is constant.
3. In series combination Potential difference across each resistor is different depending upon the value of resistance.
4. Equivalent resistance of circuit is equal to the sum of individual resistances. | | Re = R1 + R2 + R3 + R4 + …………….. Rn | DISADVANTAGE | | | If one component is fused, then the other components of circuit will not function. | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | | EQUIVALENT RESISTANCE IN SERIES COMBINATION | | | Consider three resistances R1, R2, & R3 connected in series combination with a power supply of voltage. | | Potential difference of each resistor is V1, V2, & V3 respectively. Let electric current I is passing through the circuit. | | Now | V = V1 + V2 + V3 | According to Ohm’s law V = IR
thus | IRe = IR1 + IR2 + IR3
IRe = I(R1 + R2 + R3)
IRe/I = R1 + R2 + R3
Re = R1 + R2 + R3 | | This shows that in series combination equivalent resistance of circuit is always greater than individual resistances. | PARALLEL COMBINATION | | Characteristics:
1. If there are more than one path for the flow of current in a circuit then the combination of resistances is called Parallel Combination.
2. In parallel combination current through each resistor is different.
3. Potential difference across each resistor is constant.
4. Equivalent resistance of circuit is always less than either of the resistances included in the circuit. | | ADVANTAGE | | | In parallel combination of resistors, if one component of circuit (resistor) is damaged then rest of the component of the circuit will perform their work without any disturbance. It is due to the presence of more than paths for the flow of electric current. | EQUIVALENT RESISTANCE IN PARALLEL COMBINATION | | | Consider three resistances R1 , R2 & R3 connected in parallel combination with a power supply of voltage V. | | Now | I = I1 + I2 + I3 | | according to Ohm’s law | V/R = I
Therefore,
V/Re = V/R1 + V/R2 + V/R3
V/Re = V(1/R1 + 1/R2 + 1/R3)
V/ReV = 1/R1 + 1/R2 + 1/R3
OR | |
JOULE'S LAW | | | | INTRODUCTION:
When an electric current passes through a wire heat energy is produced. It is due to the collision of electrons with the atoms. In order to continue steady current, work has to be done on electric charges. | STATEMENT:
Amount of work done on electric charge on steady current is directly proportional to amount of heat. | Work a Heat | | PROOF: | | Consider a conductor through which electric current q is passing in time t let the potential difference between two ends of wire is V. | | We know that | v = W/q
or
W = q x V_(i)
According to Ohm’s law V = IR
putting the value of V in equation (i)
W = q x IR_______(ii) | But
I = q/t
Or
Q = It | | putting the value of q in equation (ii) | W = It . IR
W = I2Rt | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | | INTRODUCTION |
| | Ohm’s law is a quantitative relation b/w potential difference and electric current. | STATEMENT | | | According to Ohm’s law, | "The electric current passes through a conductor is directly proportional
to the potential differences between the ends of conductor,
if physical conditions of conductor remain constant." | | i.e. | I a V
I = kV | | K =constant and is called "conductivity of material" | I/K = V
or
V = I/K
V = I x 1/K
Let [1/K = resistance] | V = I x R | GRAPHICAL REPRESENTATION |
| |
Chapter:17GALVANOMETER | | | | | GALVANOMETER | | | Galvanometer is an electromechanical instrument which is used for the detection of electric currents through a circuit. Being a sensitive instrument, Galvanometer can not be used for the measurement of heavy currents. | WORKING PRINCIPLE | | | Galvanometer works on the principle of conversion of electrical energy into mechanical energy. | ESSENTIAL PARTS OF GALVANOMETER | | There are five essential parts of a Galvanometer.
1. A U-shaped permanent magnet with concave poles.
2. Flat rectangular coil of wire.
3. A soft iron cylinder.
4. A pointer or needle.
5. A scale.
For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | CONSTRUCTION | | | The flat rectangular coil of thin enamel insulated wire of suitable number of turns wound on an aluminum frame is suspended between the poles of U-shaped magnet by a thin strip. One end of the wire of coil is soldered to connect to an external terminal. The other end is soldered to a loose and soft spiral. A soft iron cylinder is placed within the frame of coil. | | WORKING | | | When the current is passed through the coil it becomes a magnet. There is force of attraction is setup between the poles of magnet and coil. As a result a couple is produced in the coil and it is deflected. The current passes through the coil and the angle of deflection has a direct relation with each other. The deflection is measured by a pointer attached to the coil. |
| AMMETER-VOLTMETER | | | |
| AMMETER | | | Ammeter is an electrical measuring device, which is used to measure electric current through the circuit. | CONNECTION OF AMMETER IN CIRCUIT | | | An ammeter is always connected in series to a circuit. | SYMBOL | | | | For latest information , free computer courses and high impact notes visit www.citycollegiate.com | CONVERSION OF GALVANOMETER
INTO AMMETER |
| | Since Galvanometer is a very sensitive instrument therefore it can’t measure heavy currents. In order to convert a Galvanometer into an Ammeter, a very low resistance known as "shunt" resistance is connected parallel to Galvanometer. Value of shunt is so adjusted that most of the current passes through the shunt. Fig . Rs shunt resistance. In this way a Galvanometer is converted into Ammeter and can measure heavy currents without fully deflected. | VALUE OF SHUNT RESISTANCE |  | 
where
Rs = Shunt resistance
I = Current to be measured
Rg = Resistance of galvanometer
Ig = Current passing through
the galvanometer
| VOLT METER | | | Voltmeter is an electrical measuring device, which is used to measure potential difference between two points in a circuit. | CONNECTION OF VOLTMETER IN CIRCUIT | | | Voltmeter is always connected in parallel to a circuit. | SYMBOL | | | CONVERSION OF GALVANOMETER INTO VOLTMETER | | | Since Galvanometer is a very sensitive instrument, therefore it can not measure high potential difference. In order to convert a Galvanometer into voltmeter, a very high resistance known as "series resistance" is connected in series to Galvanometer. | VALUE OF SERIES RESISTANCE |  | 
where
RX = series resistance
V = potential difference to be measured
Rg = Resistance of galvanometer
Ig = Current passing through
the galvanometer |
| | PROPERTIES OF MAGNET | | 1. Magnets attract objects of iron, cobalt and nickel.
2. The force of attraction of a magnet is greater at its poles than in the middle.
3. Like poles of two magnets repel each other.
4. Opposite poles of two magnets attracts each other.
5. If a bar magnet is suspended by a thread and if it is free to rotate, its South Pole will move towards the North Pole of the earth and vice versa. | CHARACTERISTICS OF MAGNETIC LINES OF FORCE | | 1. Magnetic lines of force start from the North Pole and end at the South Pole.
2. They are continuos through the body of magnet
3. Magnetic lines of force can pass through iron more easily than air.
4. Two magnetic lines of force can not intersect each other.
5. They tend to contract longitudinally.
6. They tend to expand laterally. | | | For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | | FERROMAGNETIC SUBSTANCES | | Substances that behave like a magnet in the presence of a magnetic field are known as Ferromagnetic Substances.
EXAMPLES: Iron, cobalt and nickel are ferromagnetic substances. | SOLENOID | | Solenoid is a coil of wire. Solenoid is a coil wound on a cylindrical frame of iron or any material when an electric current passes through the Solenoid, a magnetic field is produced around it. It has suitable numbers of turns of wire.
Magnetic field of solenoids is given by | B = monI |  | | Magnetic field inside the solenoid is very strong and uniform but it is very weak outside the solenoid. |
ELECTRIC BELL | | | |
| MAIN COMPONENT OF
ELECTRIC BELL | | Important parts of an electric bell are :
1. Electromagnet
2. Armature
3. Spring
4. Armature rod
5. Hammer
6. Gong
|  | | CONSTRUCTION | | | One end of armature winding is connected to terminal T1 and the other to a spring, which is mounted on a soft iron strip. A rod is attached to the armature and the free end of the rod carries a small hammer, which strikes a bell. A very light spring is attached to a screw, which is joined to terminal T2. | WORKING OF ELECTRIC BELL |
| | The electric circuit is completed through a battery and push switch button connected to the terminal T1 and T2. When the push button is pressed the electric circuit is completed and the armature is attracted towards the electromagnet as a result, the small spring gets detached from the screw due to which the electric circuit is broken and the electromagnet is demagnetized. Hence, the attraction disappears and the armature is brought back by the spring to its original position. Contact of the spring with the screw is now remade, which completes the electric circuit. The action is repeated over and over again consequently. The armature vibrates and hammer attached to it strikes the gong and the bell rings and sound is produced. |
Chapter:18FUNDAMENTALS OF ELECTRONICS | | | | | ELECTRONICS |
| | Electronics is the branch of physics which deals with development of electron-emitting devices, there use and control of electron flow in electrical circuits. Electronics also deals with semiconductors, diode, rectifiers etc. | p-TYPE SUBSTANCE |
| | If a trivalent element from the IIIrd group such as Gallium (Ga) or Indium (In) is added to pure crystals of germanium (Ge) or silicone (Si), three electrons of impurity form covalent bonds with three atoms of (Ge) or (Si), while there exist a vacancy for an electron in the fourth bond. This vacant space is called Hole. This hole behaves like a positive charge and can move in the structure of substance. Such a substance is called a p-type substance. | |
| n-TYPE SUBSTANCE |
| | | If a pentavalent element from the Vth Group such as Antimony (Sb) is added to pure geranium (Ge) or silicone (Si), then four electrons of (Sb) will form covalent bonds with four (Ge) or (Si) atoms. The fifth electron of 'Sb' is free to move which makes (Ge) or (Si) a good conductor. This type of material is called n-type substance. | |
| RECTIFIER |
| A rectifier is a device which is used to convert alternating current (AC) into direct current (DC).
PN-junction diode is used as a rectifier. | RECTIFICATION |
| | The process of converting alternating current into direct current is called rectification. | FORWARD BIASING |
| | when n-type end of pn-junction is connected to negative terminal and p-type end with positive terminal of a (DC) supply, then the height of potential barrier reduces and provides easy flow of electric charge that is pn-junction conducts electricity. In this condition pn-junction is said to be Forward Biased. | | REVERSE BIASING |
| | When p-type end of pn-junction is connected to the negative terminal and n-type end with positive terminal of a (DC) supply. The height of potential barrier increases to maximum and the flow of electric charge across the junction will become zero. In this condition a pn-junction diode is called Reverse Biasing. | | DOPING | | Addition of an element of group IIIrd-A or Vth-A to Ge or Si crystals to convert them into semiconductor substance (p-type or n-type) is called Doping. Normally impurity is in very small quantity. There are two types of impurities that are added to geranium or silicon:
 DONOR IMPURITY
ACCEPTOR IMPURITY |
pn - junction diode or semiconductor diode | | | |
| INTRODUCTION |
| | A pn - junction diode is an electronic device formed from a p-type and an n-type substance semiconductor. A semiconductor diode has the property of one way conduction i.e. it allows electric current to flow in only one direction. | FABRICATION OF pn-JUNCTION | | | A pn-junction is fabricated by placing a small amount of indium on a plate or wafer of n -type germanium. Indium on heating at 550oC melts and diffuses through a small part of the n-type germanium. Indium being a p-type impurity, converts the part of the n-type germanium to p-type material. Thus a junction is formed between p-type section and an n-type section of germanium.
A brass-base is used to fix the pn-junction to which leads are attached as shown: |
| | | The whole apparatus is sealed in a glass tube or a metallic tube. |
| WORKING OF pn-JUNCTION DIODE |
| As we know that a p-type substance has excess of mobile positive charge or holes and n-type substance has an excess of negative charge or electrons, the electrons from n-type and holes from p-type sections flow across the junction and combine. In this way a layer of positive charges is formed on the n-type and a layer of negative charges on p-type material.
Due to induction of these layers a potential barrier is now developed across the junction and further flow of charges is prevented from one side to the other. |
Explain the construction and working of transistor | | | | | TRANSISTORS | | | A three terminal semiconductor electronic device is called transistor. Transistors are widely used in electronic appliances such as computers, radio, audio video equipment, bio medical instrument etc. | CONSTRUCTION | | | A transistor is a three layer semiconductor which consist a very thin central layer of one type of semiconductor material sandwiched between two relatively thick layer of second type. | |
| TYPES OF TRANSISTORS | | | | pnp-TRANSISTORS | |
| In this type of transistors n-type semi-condutcor piece is sandwiched between two piece of p-type semiconductor layers. | | npn-TRANSISTORS | | | In this type of transistors p-type semi conductor piece is sandwiched between two piece of n-type semiconductor layers. | | ESSENTIAL PARTS OF TRANSISTORS | | | There are three essentials parts of a transistor | Base: It is the central layer denoted by b.
Emitter: It is the outer layer denoted by e.
Collector: It is the outer layer denoted by c. | WORKING | | | Consider any one of the transistors for example a pnp-transistor. Let the two p-end are connected to two batteries as shown in the diagram. The forward bias causes the holes in the p-type emitter to flow towards the base which constituent Ie current. These holes cross into the n-type base, they try to combine with electrons but the base is lightly doped and is very thin. | | | Therefore only few holes combine with electrons and the remaining holes cross into the collector and generates collector current Ic. In this way almost the entire emitter current flows in the collector circuit. From the above description it is clear that: | Ie = Ib + Ic | | Thus there are two current paths through a transistor. One is the base-emitter path or input and the other is the collector-emitter path or output. | | | | | |
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tháng 12 31, 2014
placed in front of a concave lens of focal length " f " on the principle axis of the lens. Concave lens forms a virtual and erect image 
at a distance of " q " from the optical centre of the lens as shown in the diagram below.
and 
and 
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