Question

A long straight wire carries a current of π ampere. The magnetic field due to it will be 10 x `10^-5` weber/m² at what distance from the wire

[µ₀ = permeability of air]?

पर्याय

• `5 xx 10^3 mu_0` metre

• `10^4/mu_0` metre

• `5 xx 10^6 mu_0` metre

• `10^6/mu_0` metre

Answer 1

`5 xx 10^3 mu_0` metre

Explanation:

B = `(mu_0 I)/(2pi r)`

`therefore 5 xx 10^-5 =mu_0/(2pi) xx  pi/r`

`therefore r = (mu_0 xx  pi) / (10 xx 10^-5xx 2pi)`

`therefore r = 5 × 10^3 mu_0` metre