A wire of $3 ohm$ resistance and $10 cm$ length is stretched to $30 cm$ of length. Assuming that it has a uniform cross-section. Which of the following is the new resistance?

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

3 ohm

6 ohm

12 ohm

27 ohm

answer is D.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

A wire of

3 ohm

resistance and

10 cm

length is stretched to

30 cm

of length. Assuming that it has a uniform cross-section. The new resistance will be

27 ohm

.
Given
The resistance of the wire

= 3 ohm

Length of the wire

= 10 cm

When the wire is stretched,
The New length of the wire

= 30 cm

By using the formula of resistance,

R = ρ \times \frac{l}{A}

Original Resistance

= \frac{ρ \times l}{A}

where

ρ

means rho which is the constant of proportionality.
Resistance is directly proportional to the length of the wire. Resistance is inversely
proportional to the area of the cross-section.
The wire has tripled its previous length. So, its new length is "