Question

Three identical long solenoids $P,Q,R$ are connected to each other as shown in figure. If the magnetic field at the center of $P$ is $2.0$ $T$, what would be the field (in $T$) at the center of $Q$? Assume that the field due to any solenoid is confined within the volume of that solenoid only.

Answer 1

As the solenoids are identical, current i in Q and R will be equal and $i_Q=\frac{i_R}{2}=\frac{i_P}{2}$
$\therefore B_Q=B_R=\frac{B_P}{2}$ since current is half.
Given $B_P=2T$
$\therefore B_Q=B_R=\frac{B_P}{2}=\frac{2}{2}T=1T$