Question

The magnetic induction at a distance 'a' from a long straight wire carrying a current. I has magnitude

• A. $\frac{{\mu }_0}{4\pi }\times \frac{I}{a^2}$
• B. $\frac{{\mu }_0}{4\pi }\times \frac{I}{a}$
• C. $\frac{{\mu }_0}{4\pi }\times \frac{2I}{a}$
• D. $\frac{{\mu }_0}{4\pi }\times \frac{I}{2a}$

Answer 1

The correct option is C $\frac{{\mu }_0}{4\pi }\times \frac{2I}{a}$

Given: Distance from the wire is "a" carrying current "I"

Solution:

Formula for magnetic induction for a long wire carrying current I at distance r is $\frac{\mu I}{2\pi r}$

So by substituting values in the formula we get$\frac{\mu I}{2\pi a}$

By multiplying both numerator and denominator by 2 we get $\frac{2\mu I}{4\pi a}$

The correct opt : C