HARD
12th West Bengal Board
IMPORTANT
Earn 100

Derive the relation between current density J and potential difference V across a current-carrying conductor of length l, area of cross-section A and the number density n of free electron density.

Important Questions on Current Electricity

HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 20
 Use Kirchhoff's rule to obtain the balance condition in a Wheatstone bridge.
HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 20
 Draw a circuit diagram for determining the unknown resistance $R$ using metre bridge. Explain briefly its working, giving the necessary formula used. 
HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 21
Write the underlying principle of potentiometer. Draw the current diagram of the experimental set-up used for determining the internal resistance of a cell by potentiometer. Write the necessary formula used.
HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 22
 State, with the help of a circuit diagram, the working principle of a metre bridge. Obtain the expression used for determining the unknown resistance.
EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 22
 What happens if the galvanometer and cell are interchanged at the balance point of the bridge?
EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 22

 Why is it considered important to obtain the balance point near the mid-point of the wire?

MEDIUM
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 1
A metallic wire 10 cm long has a resistance of 5Ω. If the wire is now stretched so that its length is doubled, what happens to the value of the resistance? (Assume that the volume and specific resistance of the wire remain unchanged) 
MEDIUM
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 2
A wire of resistance 5Ω is stretched 20%. If the volume remains constant, find the new resistance.