Question

In the given circuit, connect a nichrome wire of length ‘L’ between points X and Y and note the ammeter reading.
(i) When this experiment is repeated by inserting another nichrome wire of the same thickness but twice the length (2L), what changes are observed in the ammeter reading?
(ii) State the changes that are observed in the ammeter reading if we double the area of cross-section without changing the length in the above experiment. Justify your answer in both the cases.

Answer 1

Answer:

(i) The Current reading in the Ammeter Decreases as the resistance in the Circuit becomes Doubled as the Length is doubled.

(ii) The Current Reading in the Ammeter Increases as the Resistance in the Circuit becomes Halved as the Area Of Cross Section is Doubled

Answer 2

(i) Ammeter reading is half of what it was originally.

(ii) Ammeter reading is double of what it was originally.

Explanation:

(i) When the length is increased to 2L, resistance increases, so the current decreases. Hence the ammeter reading will decrease.

R = pL/A will change to 2pL/A

When p and A are constant and L increases to 2L, resistance will increase twice the initial value.

V = IR

When resistance doubles, current I will be halved its original value.

(ii) When the cross-section area is doubled to 2A, resistance decreases by half as p and L are constant.

R = pL/A will change to pL/2A

V = IR

When resistance is halved, current I will double.

The ammeter reading will increase to double what it was initially.