## CBSE Physics– important diagrams electromagnetic induction and AC

CBSE Physics Class XII Important diagrams from Electromagnetic Induction and AC can be downloaded here.

The students should note that the diagrams are to be as per the text books and therefore we have taken care to follow the text book in preparing the files.

The following diagrams are included in the file

#### ELECTROMAGNETIC INDUCTION

• Faraday’s Experiment on Electro Magnetic Induction
• Illustration of Lenz’s law
• Motional emf
• Eddy current
• Mutual inductance of two solenoids
• AC generator

#### ALTERNATING CURRENT

• AC circuit with R only
• AC circuit with L only
• AC circuit with C only
• LCR AC series circuit
• Impedence diagram
• LC oscillations
• Resonance in LCR series circuit
• Transformer

ELECTROMAGNETIC INDUCTION  — Important diagrams from emi

ALTERNATING CURRENT — important diagrams from ac

## Questions asked in Physics Viva Voce for Class 12 Physics Practical

Q1. Why are the resistances used in a resistance box is like 1,2,2,5,10,20,20,50,100,200,200,500,1000,2000,2000,5000 etc?

Ans: In this arrangement all natural numbers upto 10000 ohms (and above) can be realized.

1, 2, 2+1=3,2+2=4,5,5+1=6,5+2=7,5+2+1=8,5+2+2=9 etc

Try it yourself to get all numbers from 1 to 10000

Q2. Why wire is double folded in resistance box?

Ans: The resistance wires in resistance box and in standard resistances are double folded and then coiled so as to nullify the effect inductance. When double folded and coiled, in one half the current will be clockwise and in next half the current will be anticlockwise. Therefore, the magnetic induction created by one half will be cancelled by the other half.

Q3. we make coil of wire when finding resistance of wire through metre bridge ?

Ans: This is not correct. If it is to be coiled, it should be done as in Q1.

Normally the wire is stretched on a half meter scale and fixed with terminals (or arranged in some other manner)

If you feel that the wire need to be coiled, then take  care to avoid the magnetic effect. ## REVISION MATERIAL FOR CBSE CLASS 9 SCIENCE (PHYSICS) FOR SA 1

PHYSICS (MOTION)

Points to remember:

• A body is said to be at rest if it does not change its position with respect to its surroundings
• A body is said to be in motion i i changes its position with respect to surroundings
• we can perceive the motion of certain bodies directly such as a cycle moving on road.
• we can perceive the motion of certain other objects by indirect evidences.Motion of air can be observed from movement of dust particles and the branches of trees.
• rest and motion are relative terms.a body appearing to be at rest to one person may appear to be in motion of another person
• Speed is the ratio of distance covered to the time taken.speed is scalar quantity
• Speed is never negative and is zero when the body is at rest
• Velocity is the rate of change of displacement with time.It is a vector quantity
• Velocity may be zero,negative or positive even when tho body is moving. Its S I unit is m s -1
• Acceleration is the rate of change of velocity of a body.Acceleration is a vector quantity. Its  S I unit is m s -2.
• Motion . A body is said to be in motion  if it changes it position with respect to surroundings
• Uniform motion. Motion is said to be uniform if body covers equal distance in equal intervals of time however small these intervals may be.
• Non uniform motion.Motion is said to be nonuniform if the body covers unequal distances in equal intervals of time.
• Distance covered by body is the actual length of path covered by the body. It is measured in metre (in SI). Its CGS unit is centimetre (cm). Distance can never be negative. It is a scalar quantity.
• Displacement is the distance covered by a body in certain direction from starting point to final point. Displacement is a vector quantity and may be positive, negative or zero.
• Speed is the ratio of distance covered to the time taken