A soft iron ring has a mean diameter of 0.020 m and area of cross-section 5 x 10^-4 m². It is uniformly wound with 2000 turns carrying a current of 2 A and the magnetic flux in the iron is 8 x 10³ Wb. What is the relative permeability of iron?

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

2000

1000

8000

4000

answer is B.

(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

We know that $B = \frac{μin}{2 πr}$
$\begin{array}{l} ∴ ϕ = BA = \frac{μin}{2 πr} \times A \\ or ϕ = \frac{μ \times 2 \times 2000}{2 π \times 0 \cdot 01} \times 5 \times 10^{- 4} \\ or 8 \times 10^{- 3} = \frac{10 μ}{π} \\ or μ = 8 π \times 10^{- 4} {Hm}^{- 1} \\ Now μ_{r} = \frac{μ}{μ_{0}} = \frac{8 π \times 10^{- 4}}{4 π \times 10^{- 7}} = 2000 \end{array}$