Question

A wire of length L and resistance R is stretched so that its length it’s doubled keeping the volume same. How will the (a) Resistance change (b) Resistivity change?

Answer 1

Answer:

1. resistance becomes twice
2. 2 times

MARK as BRAINLIEST please

Answer 2

Answer:

Since the length of the wire is doubled, its area of cross-section is halved so as to keep the volume of the wire constant. Now the resistance of the wire is proportional to length of the wire, since the length of the wire is doubled its resistance also doubles due to doubling of the length.

Explanation:

We have

Resistance= Resistivity x length/area

When the wire is stretched to double the length , the area of cross section gets reduced to half.

So

New Resistance = Resistivity x 2length/area/2

I.e,

New resistance = (Resistivity x length/area)x4

i.e, New resistance = Resistance x 4

So when the wire is stretched, the resistance multiplies by four times.

Hope you understood. Keep exploring.

Edit: Why does area gets halved when length is doubled?

Volume of the wire remains constant before and after the stretching.

Volume = Cross sectional area x length

When length is doubled, area must be divided by two to keep the volume constant.

Hope you understood.