Book Online Demo

Check Your IQ

Try Test

Courses

Offline Centres

Calculate the resistance of a constantan wire of length $2 m$ and radius $0.1 mm$ . Given that resistivity of constantan is $49 \times 10^{- 8} Ωm$ .

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

31.8 Ω

32.1 Ω

20 Ω

31.1 Ω

answer is D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

The resistance of a constantan wire is

31.1 Ω

.
Given data in the problem,
Length of wire,

l = 2 m

Radius of wire,

r = 0.1 mm

Resistivity of constantan,

ρ = 49 \times 10^{- 8} Ωm

Area of wire,

A = π r^{2}

\Rightarrow A = 3.14 {\times 0.1}^{2}

By using the formula,
Resistance

R = ρ \cdot \frac{L}{A}

\Rightarrow R = 49 \times 10^{- 8} \times \frac{2}{3.4 * {0.1}^{2}}

\Rightarrow R = 31.1 ohm

So, the resistance of constantan is

31.1 ohm

JEE

NEET

Foundation JEE

Foundation NEET

CBSE