Complete Physic As

7/29/2019 Complete Physic As

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Physics (9702)

Concise Notes for A Levels Students

Muhammad Hassan Nadeem P a g e | 1

Units and Dimensions

Physical QuantitiesPhysical quantity is physical property that can be measured.

Base Quantity

Seven arbitrarily chosen physical quantities are called base quantities and its units

are known as base units.

Basic Quantity Base Units Symbols

Length Metre m

Mass Kilogram kg

Time Second s

Electric Current Ampere A

Temperature Kelvin K

Amount of Substance Mole Mol

Luminous Intensity Candela cd

Derived Quantites

All physical quantities other than base quantities are called derived quantities, and

its unit is called derived unit. For example speed is a derived quantity and m/s is its

derived unit:

Quantity Unit Name Symbol


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Prefix Factor Symbol

Pico 1012 p

Nano 109 n

Micro 106

Milli 103 mCenti 102 c

Deci 101 d

Kilo 103 k

Mega 106 M

Giga 109 G

Tera 1012 T

MeasurementsReading

Reading is a single determination of the value of an unknown quantity. It is the

actual reading taken during an experiment.

Measurement

Is the final result of the analysis of a series of readings.

Vernier Calipers

1. Read the value of the main scale which is just to the left of 0 reading on theVernier scale (12 mm in this case).

2. Read the value of the Vernier scale which exactly coincides with the mainscale (3 in this case).

3. The total reading would be


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Micrometer screw gauge

Reading = Linear Scale reading + (Coinciding Circular scale reading x 0.01) mm

= 2.5 + (46 x 0.01)

= 2.5 + 0.46

= 2.96 mm

Systematic Errors

Uncertainties in the measurement of physical quantities due to instrument, faults in

the surrounding conditions or wrong assumptions made by the observer.

Size of error is roughly constant and measurement obtained is either always greateror always less than the actual value.

Examples of Systematic Error

1. Zero Error2. Reaction time of observer3. Due to instruments

a. A watch is fastb. Calibration at certain temperatures and used in under different

temperatures.

4. Errors due to wrong assumptions, e.g. value of g taken as 10m/s2Systemic Errors cannot be reduced by taking average.

Systematic Errors can be reduced by

Taking measurements carefully Using different instruments Using different methods Checking zero error Checking stopwatch with another stopwatch


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Random Error

Uncertainties in measurement made by the observer or person who takes the

measurement.

Random error can be positive or negative, and its magnitude is not constant.

Example of Random Error

1. Errors due to parallax error2. Changes in temperature during an experiment3. Different pressure applied when closing the gap of micrometer screw gauge

when measuring a soft object.

Random Errors can be reduced by

Taking average

Precision

A measurement is said to be precise if mean deviation of readings is smaller(the

readings are close to each other and not spread over a long range).

Diameter Mean Diameter Deviation Mean Deviation

0.38

0.02

0.024

0.36 0.04

0.40 0.00

0.44 0.040.42 0.02

Precision can be improver my:

Using a hand lens. A plane mirror behind the pointer. The observer reads the scale when the

pointer is directly on top of its image in mirror. This is done to avoid parallax

error.

AccuracyA measurement is said to be accurate if it is close the actual value.

Accuracy is given by the percentage error. The Smaller the percentage error, the

higher the accuracy.

Calculating Percentage Error


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Precise and

Accurate

Accurate but not

Precise

Precise but not

Accurate

Not Precise and

not Accurate


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Calculating Compound Errors

If

If If

[ ]If

[ ]If

[ ]

Addition, Subtraction, Multiplication and Division of constants have no effects on

compound errors.

Vectors

Scalar Quantities

A scalar quantity is one which can be described fully by just stating its magnitude.

For example: mass, time, length, temperature, density, speed, energy and volume.

Vector Quantity

A vector quantity is one which can only be fully described if its magnitude and

direction are stated.

For example: displacement, velocity, acceleration, force, momentum, magnetic flux

density and electric intensity.


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Addition of Vectors

1. Parallelograms of vectors

2. Triangle of Vectors (head to tail)

Resolving a Vector

Vertical Component of R = R sin

Horizontal Component of R = R cos


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Triangle of Forces

If three forces acting on a point can be

represented in magnitude and

direction by the three sides of a triangle

taken in order, then the three forcesare in equilibrium.

Static Equilibrium

Moment of a Force

Turning effect of force about an axis is called torque or moment of a force. SI unit of

moment is Nm.

Equilibrium of a body

A body is in equilibrium if:

1. The resultant force is zeroAND

2. Sum of Moments of forces about any axis is zeroCouple

A couple consists of two equal and opposite forces when its line of action is not

along the same line.


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Centre of Gravity

The center of gravity G of an abject is the point where the line of action of weight

passes.

It is the point where the weight of the object appears to be acting.

Stability

An object is stable if

1. It has a larger base.2. Its center of gravity is lower.

Kinematics

Three types of motion

Translatory motion

Also known as linear motion is motion along a straight line.

Rotatory motion

Spinning or turning motion that takes place around an axis, without a change in

linear position is called rotatory motion.

Vibratory


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When an object is displaced from its fixed position and made to move to and fro

periodically, it is known as vibratory motion. A vibratory motion happens when a

particle is vibrated. Vibratory motion is also called as oscillatory motion

DistanceTotal length covered by a body during its motion. Scalar quantity SI unit is m.

Displacement

Shortest Distance covered. Vector quantity Si unit is m.

Speed

Distance covered per unit time. Scalar quantity SI unit is m/s.

Uniform/Constant speed

Equal distance covered in equal interval of time

Velocity

Displacement traveled per unit time. Vector quantity Si unit is m/s.

Acceleration

Rate of change of velocity. Vector quantity Si unit is m/s2.

Equations of Motion


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Distance-Time Graph

Gradient (slope) of Distance-Time graph shows velocity

Velocity-Time Graph

Area under Velocity-Time Graph shows distance covered. Gradient (slope) of Velocity-Time Graph gives acceleration.


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Projectile Motion

Horizontal component of velocity stays same.

Vertical component of velocity changes due to gravitational force.

Dynamics

Force

Force can be defined as rate of change of momentum. It is a vector quantity and its

SI unit is N.

Inertia

It is a property of material objects due to which they oppose any change in their

original state. It depends on mass of body.

Newtons First Law of Motion

A body continues its initial state of rest or uniform motion unless it is compelled to

change that state by an external force.

Newtons Second Law of Motion

When an unbalanced force acts on a body its produces acceleration in the body in

the direction of force. The magnitude of the acceleration is directly proportional to

the applied force and inversely proportional to the mass of body.

Newton

A force is said to be one newton when it produces an acceleration of 1 m/s2 in a


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body of mass 1 kg.

Newtons Third Law of Motion

To every action there is equal and opposite reaction.

Momentum

Linear momentum of a body is the product of its mass and its velocity.

It is a vector quantity and SI unit is Ns or Kg m/s.

Principle of Conversation of Momentum

The total linear momentum of an isolated system is constant.

Elastic Collision

A collision in which total kinetic energy stays constant.

Relative speed of approach is equal to relative speed of separation.

If bodies of same mass collide their speeds are interchanged.

Inelastic Collision

A collision in which total energy stays constant but kinetic energy changes.

Work

Work done is product of force and the distance in the direction of force.

It is scalar quantity and its SI unit is Joule, J.

Joule

Work done is said to be 1 J when the force of 1N displaces a body though 1 m in its

direction.

Energy

Energy is ability to do work.

Kinetic Energy

Energy possessed by a body due to its motion

Potential Energy

Energy possessed by a body due its physical condition or motion


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Internal Energy

Principle of Conservation of Energy

Total energy of an isolated system stays constant.

Power

Power is the rate of doing work. Its SI unit is watt or J/s.

Efficiency

Electricity ASElectric Current

Current is rate of flow of electric charge.

SI unit is Ampere, A.

where n = number of electrons

and e = charge on one electron

Potential Difference

The potential difference between two points in a circuit is the work done to move a

unit charge from one point to another.


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EMF

EMF of a source is the work done to move a unit charge around a complete circuit.

Ohms Law

Ohms law states that the current passing though the conductor is directly

proportional to the potential difference across it, provided that temperature and

other physical conditions stays same

Ohmic Conductor

Ristance Constant

ThermistorResistance

decreases

Filament lamp

Resistance Increases

Resistance

It is the ratio between V and I flowing through a circuit.

It is the ratio between V and I flowing

through a circuit.

Increasing temperature of a wire leads

to increasing resistance.

Factors on which Resistance depends

Nature of material. Resistivity of conductor. Cross-sectional area A. Inversely proportional Length l. Directly proportional


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Series combination of resistors

Same current passesthrough all resistors.

V = V1 + V2 + V3 R = R1 + R2 + R3

Parallel Combination

V stays same

Thermistor

Thermistors are devices made from

semiconductors, break the rule we've

just explained (typical) and reduce

their resistance as temperatureincreases. This is because the extra

energy makes the atoms release

electrons, allowing them to move more

easily, this in turn reduces the

resistance.

Light Dependent Resistor LDR

Light-dependent resistors also decrease their resistance when energy is given, but

this time the energy needs to be given as light energy.

Internal Resistance

Cell is not perfect, some energy is wasted inside the cell, this is due to resistance


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inside the cell.

Where:

V= Voltage across external circuit.

E= emf of cell

I= Current through cell

r= Value of internal resistance

Ir= P.d across internal resistor

Kirchhoffs First Law

The vector sum of current entering a junction in a circuit is zero.

This law follows the principle of

conservation electric charge.


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Kirchhoffs Second LawAround a closed loop, the vector sum of the Emf is equal to the vector sum of the

products of current and resistors.

This law is based on law of conservation

of energy.


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Elasticity

ElasticityIt is the ability of a body which enables it to regain its original dimensions when the

deforming force acting on it is removed.

Elastic Limit

Materials are only elastic up to a certain limit known as elastic limit. Beyond this point

material would not return to its original dimension when deforming force is removed.

Hooks Law

Within the elastic limit the extension or compression is directly proportional to the

applied force.

Stress

It is the force applied per unit area of cross-section. Its unit is N m-2 or Pa.

Strain

It is defined as extension per unit length. Strain does not have a unit.

Young ModulusThe ratio of stress and strain is known as Young Modulus. Its unit is N m-2 or Pa.

(

)


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Gradient of Stress-Strain graph gives

youngs modulus.

Area under force-extension graph gives

Strain Energy

Behaviour of a wire under stress

Limit of proportionality

It a point beyond which extension is not proportional to force and stress is notproportional to strain.

Elastic Limit

Slightly beyond limit of proportionality is elastic limit. Up to elastic limit, any work done

can be fully recovered.

Elastic Deformation

Wire returns to its original length.

Plastic Deformation

After elastic limit is exceeded, wire does not return completely to its original length.


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Yield point

At lower yield point plastic flow begins. Atomic planes in the wire slide over each

other, and wire narrows down uniformly.

Beyond upper yield point extension is permanent and a small amount of forceapplied causes great extension.

Ultimate tensile strength

It is the point of maximum stress where wire has its greatest strength.

Beyond ultimate tensile strength wire narrows unevenly, forming necks and

eventually breaks.

Brittle Material

Do not show plastic deformation and break immediately once elastic limit is

exceeded. For example glass.

Ductile Material

Undergo plastic deformation before breaking

Glass Copper

Rubber Polythene


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Experiment to determine the Young modulus of a metal wire

States of Matter

Solid

Made up of molecules arranged closely in fixed pattern. Molecules vibrate about their mean positions The force of attraction between molecules are very strong Solids have fixed shape

Liquids Made up of molecules close together. Molecules are able to slide over each other. Takes shape of container.

Gas

Molecules are in constant random motion. Intermolecular distance is very large compared to size of molecule.

Gas molecules collide with each other and with walls of container (elastically)exerting pressure.

Crystalline Solids

Atoms are arranged in fixed repetitive manner over a long distance. For example

NaCl.

Amorphous Solids

Also known as non-crystalline solids, it lacks long-range order characteristic of crystal

(atoms are repeated only over a short range).

Waves

Displacement

Amplitude

Phase Difference


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Period

Frequency

Wavelength

Speed

Progressive waves distribute energy from a point source to a surrounding area. They

move energy in the form of vibrating particles or fields

Transverse Waves

vibrations are perpendicular to the wave motion - so if the wave is travelling

horizontally, the vibrations will be up and down. For example, light and water.

Longitudinal Waves

vibrations are parallel to the wave motion - so if the wave is travelling horizontally,

the particles will be compressed closer together horizontally, or expanded

horizontally as they go along (we call the expanded bit a rarefaction). The particle

movement is a series of compressions and rarefactions. For example, sound and

some earthquake waves.

Diffraction

Diffraction is the spreading out of waves as they pass through a gap or by an

obstacle.

1. The smaller the gap the greater the diffraction.2.

The longer the wavelength the greater the diffraction.


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Wavelength remains same before and after the diffraction.

Coherence

Coherent waves are waves with a constant phase difference. (Note: They don't haveto be in phase for this to be true.) They will have the same frequency and

wavelength (they are normally produced from one source).

When two waves meet they will interfere and superpose. After they have passed

they return to their original forms. This is true if they are coherent or not.

At the point they meet, the two waves will combine to give a resultant wave whose

amplitude (or intensity) may be greater or less than the original two waves.

The resultant displacement can be found by adding the two displacements together:

This is called the Principle of Superposition.

If two waves of the same type and the same frequency combine so that the crest of

one coincides with the trough of the other, they will completely cancel each other

out. This is called destructive interference.Alternatively, the two waves could

combine when their crests coincide; then there would be constructive

interference and the resultant amplitude would be equal to the sum of the separate

amplitudes:

Superposition will occur whether waves are coherent or not. (However, if the waves

are coherent, they will interfere to produce a fixed pattern.)

The same rules apply... the resultant displacement at any point is always the sum of

the separate displacements of the wave at that point:


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Diffracting Grating

Standing/Stationary Waves

Polarization

Transverse waves can oscillate in any plane. Polarization is the process by which the

oscillations are made to occur in one plane only.

This is done by passing the waves through a 'grid' so that only the waves that can fit

through the slits can continue through:


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Longitudinal waves cannot be polarised.

Circular Motion

Angular Displacement

Angle subtended by an arc at the

center of the circle. It is measured in

radians.

Radian

Angular displacement is said to be one radian when length of arc is equal to the

radius of circle

Angular Velocity

Rate of change of angular displacement

Frequency f

The number of rotation per second made by the rotating object


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Centripetal Force

It is the force which compels the body to move in a circle. Centripetal force always

directs towards the center of the circle. During circular motion whatever be theforces acting on the body their resultant is centripetal force.

Motion in Horizontal Cirle

In case of horizontal circle tension in the string provides necessary centripetal force

so

Motion in Vertical Cirlce

At the top of ci rc le:

Tension and weight are in same

direction

At the bottom of ci rc le:

Tension and weight are in opposite

direction


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Centripetal Acceleration

Acceleration caused by centripetal force.

Universal Gravitation

Newtons law of Universal Gravitation

Newtons law of Universal Gravitation states that the force of attraction between

two objects is directly proportional to the product of the masses of the objects and

inversely proportional to the square of the distance between them.

G is known as universal gravitation constant. Relationship between G and g


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Gravitational Field

It is the force field around a mass, when another mass is introduced into the field it

experiences a force.

Gravitational Field Strength

The gravitational field strength, g at a point in a gravitational field is defined as the

gravitational force of attraction per unit mass at that point.


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Gravitation Potential

The gravitation potential, V at a

point in a gravitation al field is

the work done by the

gravitational attraction to bring

a unit mass from infinity to that

point.

The gravitation potential at

infinity is assumed to be zero

and its value decreases as mass

approaches closer to earth

(becomes negative). It is scalar

quantity and its unit is J/Kg

Equipotential Surface

The surface where all points on it has the same gravitation potential.

Gravitational Potential Energy

The gravitational potential energy U of a body of mass m at a point in gravitational

field is defined as work done to bring the body from infinity to that point. Its unit is

joule J.

Motion of Satellite

Gravitational attraction provides centripetal force so:


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Energy of Satellite

( )

( )


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Geostationary Satellite

Satellite which orbit around the earth above the equator with period of 24 hours.

These satellites orbit in the same direction as rotation of earth (west to east). These

satellites provide continuous link for the communication. These satellites do not need

to be tracked.

Simple Harmonic Motion

A body is said to be in simple harmonic motion if its acceleration is directly

proportional to its displacement from fixed point (equilibrium position) and is always

directed towards that fixed point.


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Relation SHM and Circular Motion


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Energy of particles executing SHM

Kinetic energy is maximum when x=0

Potential Energy is maximum when x=x0


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Damping Effect

The effect of resistive forces in removing energy in vibration object in form of heat to

the surrounding.

Damped Oscillations

Oscillations where the amplitudes become smaller and smaller are known as

damped oscillations.

Light Damping

If the resistive forces are small then system is said to be lightly damped. Amplitude of

oscillation is decreases gradually. It is only after a large number of oscillations that


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the system stops oscillating. Amplitude decreases exponentially with time.

Critical Damping

If the damping is just sufficient to prevent oscillation, but yet not too great to

indefinitely delay returning to original position then the system is said to be critically

damped.

Heavy Damping

If the resistive forces are very large then the system is said to be heavily damped.

After displacement return to original position takes a very long time.


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Advantages of damping

Suspension system in car. Good system is one which is slightly under critical damping.

Forced Oscillations

Oscillations which are under the influence of an external periodic force are known

as forced oscillations. The frequency of such a system is the same as the frequency

of the external periodic force (known as drivers frequency).

ResonanceThe phenomenon in which the amplitude of the oscillating system becomes very

large when drivers frequency becomes equal to the natural frequency of the

oscillating system is known as resonance.


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The sharpness of the peak depends upon the resistive forces acting on the system,greater the resistive force smaller the amplitude of the vibration and flatten will be

the peak.

One effect of the damping is to decrease the effect of resonance so greater the

damping smaller the amplitude of vibration at the resonance frequency.

Advantages of Resonance

1. Radio tuning circuit: When tuned, radio waves have same frequency asfrequency of the electrical oscillations in the circuits of receiver.

2. Cooking of Food in microwave oven: In ovens microwave with the frequencysimilar to the natural frequency of water molecules are used.

3. MRI:Disadvantages of Resonance

1. Vibrating parts of the mechanical equipment might break.2. Collapse of suspension bridge.


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Motion of mass attached to a spring

Hooks Law: F=Kx

When mass is released it accelerates towards equilibrium position.

Hence motion is SHM

Comparing with

Motion of mass attached to two similar springs.

When the mass is in equilibrium the extension in each spring is equal to e.

When the mass is displaced a small distance x to the right, the magnitude of

restoring force is given by.

When mass is released it accelerates towards equilibrium position


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Hence motion is SHM

Electrostatics

Coulombs Law

Coulombs Law states that the force between two point charges is directly

proportional to the product of the charges and inversely proportional to the square

of the distance r between them.

0 = Epsilon knot = Permittivity of free space or vacuum = 8.85 x 10-12 Fm-1

It the charges are not in vacuum then

r=Relative permittivity of that medium with respect to vacuum. Its value is always

>1.

Electric Field

It is a force field which exists around a charge when another charge is introduced in

experiences a force.

It is a vector and is represented by lines of force. The direction of electric field is from

positive to negative.

Electric Field Strength

Electric field strength E at a point in an electric field is the force per unit charge

acting on a positive test charge (q) placed at that point. Its a vector quantity and

its unit is N/C or V/m.


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point charge.

Inside the sphere electric field E=0.

Capacitor

A capacitor is a device for storing electric charge.

It consists of two parallel metal plates with an insulator (known as dielectric) present

between the plates.

Capacitance

Capacitance is the ability to store charge. It is the ratio between the charge Q

stored on any one plate of capacitor and the potential difference V across it. SI unit

is Farad F.

Capacitance depends on

A = Area of the plate d = Separation between plates 0 = Permittivity of free space (nature of dielectric)

Combination of Capacitors

Series Combination

Charge stored on each capacitor is same = Q V=V1 + V2 + V3

If only two capacitors then Parallel Combination

Potential difference across each capacitor is same = V Q = Q1 + Q2 + Q3 C = C1+ C2 + C3

NOTE:


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Energy stored in charged capacitor

Forces in Magnetic Field

Force on Charged Particles

Where:

Q=charge of particle

v=velocity of particle

B=Magnetic flux density

=Angle between velocity and magnetic field

Force on Current Carrying conductor

Where:

I=current passing through conductor

l=length of conductor

B=magnetic field density

=Angle between direction of flow of current and magnetic field

If the particle goes undeflected


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When a charged particle enters a magnetic field we now know it will be forced to

change direction. If it stays in the field it will continue to change direction and will

move in a circle. The force produced will provide the centripetal force on themoving particle.


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Flemings Left Hand Rule

Force of repulsionbetween current

carrying parallelconductors when

current flowing is in

opposite direction.

Force of attraction

between current

carrying parallel

conductors whencurrent flowing is in the

same direction.

Magnetic field pattern in case of a current carrying solenoid


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X= Current into the paper

0 = Current out of the paper

Magnetic flux density

Magnetic flux density is the force per unit length on a straight conductor carrying

unit current normal to the magnetic field. Its unit is Tesla, T.

Tesla

Magnetic flux density is said to be 1 Tesla when force of 1N is experiences by a

conductor of 1m carrying a current of 1A placed normal to the magnetic field.

Ac current

The main feature of AC is that the direction of flow changes from one direction to

another.


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Full-Wave Rectification


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The output is not pure DC so, put a capacitor (known as reservoir capacitor) across

(parallel to) the resistor and when the supply voltage across the resistor drops

towards zero the capacitor delivers some extra current through the resistor in the

correct direction. This is called 'smoothing'


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Hall Effect

It is the phenomenon in which transverse potential difference is set up in a

conductor carrying current in a magnetic field.

Hall Probe

Hall probe uses hall effect to measure magnetic flux density. It consists of small piece

of semi-conductor through which constant current I is flowing. A sensitive voltmeter is

connected to the terminals to measure Hall p.d. Hall probe must be positioned

perpendicular to the magnetic field. Hall probe is calibrated by placing it in known

magnetic field (B0) and noting p.d (V0) produced.

Advantages of Hall Probe

Size of Hall probe is very small and can be used to measure magnetic fluxdensity in small isolated areas.

It is very sensitive so it can measure small changes in magnetic flux.

Electromagnetic Induction

Effect of producing an electric current using magnetism is known as

electromagnetic induction.

The current produced is known as induces current.

Magnetic flux through an area A perpendicular to magnetic field of flux density Bis given by:

Magnetic flux linkage through a coil of N turns with its plane perpendicular to themagnetic field density B is given by:

SI unit of magnetic flux is Weber (Wb).

Magnetic flux density

Magnetic flux per unit area.


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SI unit is Wb/m2.

Faradays Law

When the magnetic flux linkage though a circuit changes, the emf produced is

directly proportional to the rate of change of flux linkage.

Lenzs LawThe direction of the induced current is such as to oppose the change which gives

rise to it.

Lenzs law is a direct consequence of the principle of conservation of energy. The

electrical energy produced in electromagnetic induction is the result of the

transformation of mechanical energy in the form of work done into electrical

energy.

Negative sign in the equation implies that induced emf opposes the rate of change

of magnetic flux linkage.

-t graph, B-t graph and I-t graph are same.

Mutual Induction

Mutual Induction is the phenomenon in which E.M.F. is induced in one coil due to

the variation of current in nearby coil.

Self-Induction

Self-induction is phenomenon in which an E.M.F is induced in the same coil (Primary

Coil) in which current is changing.

Self-induction results in Back E.M.F or Eddy Current


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Transformer

Transformer is a device used to increase or decrease the A.C voltage.

Soft Iron core is used:

So that magnetic field lines can pass through easily. Because it is easy to magnetize and de magnetize.

Where

Np and Ns are the number of turns in Primary and Secondary coil respectively

B is the magnetic flux density

A is the Cross-Sectional area of core

Transmission of A.C current

It is recommended to transmit the power at high voltage to minimize power loss.


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Threshold Frequency, f0

The minimum frequency of incident radiation required to cause the emission of

photoelectrons from the metal surface is known as threshold frequency.

Work Function

The minimum energy needed for an electron to escape from metal surface.

Einstein Photoelectron Equation

Note:

No photoelectron emits whatever the intensity of light be, if the frequency of

incident radiation is less than threshold frequency

After threshold frequency when the intensity of elimination is increased the number

of photoelectrons emitted per second also increases (i.e. photoelectric current

increases).


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The increase in photoelectric current is due to higher rate of emission of

photoelectrons and not because the photoelectrons have more energy.

Maximum kinetic energy does not change unless the fof the incident radiation or

metal surface is changed.


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Experiment to find Maximum Energy

A reverse p.d. is applied (cathode is connected with positive terminal), the p.d. is

slowly increased until the reading of Ammeter falls to zero. This stopping p.d. (Vs) isrecorded by the voltmeter.


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Physics (9702)



Momentum of a Photon

Radiation Pressure

Radiation pressure is the pressure exerted upon any surface exposed to

electromagnetic radiation

As photon is absorbed by the surface the final momentum is zero so

If n= number of photons incident per second


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Physics (9702)


Radioactivity

Complete Physic As

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