Question

The magnetic induction at a point P which is at a distance of 4 cm from a long current carrying wire is `10^(-8)` T. The induction at a distance 12 cm from same current carrying wire is
A. `3.33 xx10^-9` tesla
B. `1.11xx10^-4` tesla
C. `3xx10^-3`tesla
D. `9xx10^-2` tesla

Answer 1

Correct Answer - A
`B=(mu_0I)/(2pia)because Bprop(1)/(a) (B_2)/(B_1)=(a_1)/(a_2)`
`B_2=(4xx10^-2xx10^-8)/(12xx10^-2)=3.3xx10^-9T`