Question

If the area of cross-section of a resistance wire is halved, then its resistance becomes :; A. one-half; B. 2 times; C. one-fourth; D. 4 times

Answer 1

Answer:

B. 2 times

Explanation:

As per the question,

We know that resistance of a wire is mathematically given by the formula:

$R=\rho \frac{l}{A}$

Where,

R = resistance of the wire

ρ = resistivity of the wire

l = length of the wire

A = cross-sectional area of the wire

Now according to question cross-sectional area of the  wire is halved that is

New area = A/2 = 0.5 A

∴ $New \ R = \rho \frac{l}{0.5A}$

$New \ R=2 \times \rho \frac{l}{A}$

So we can see that new resistance becomes two times of original resistance of the wire.

Hence, the correct option is (B).

Answer 2

Answer:

If the area of cross-section of a resistance wire is halved, then its resistance becomes 2 times