Question:
Four identical long solenoids $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and $\mathrm{D}$ are connected to each other as shown in the figure. If the magnetic field at the center of $\mathrm{A}$ is $3 \mathrm{~T}$, the field at the center of $\mathrm{C}$ would be : (Assume that the magnetic field is confined with in the volume of respective solenoid).
Correct Option: , 4
Solution:
$\phi \propto \mathrm{i}$
$\Rightarrow B \propto i$
so, field at centre of $\mathrm{C}=\frac{3}{3}=1 \mathrm{~T}$