Electromagnetic Induction Part 2

Concept:Lenz's law: induced current opposes the change in magnetic flux that causes it.Explanation:View the coils from the right side along their common axis. Coil $C_1$ carries current anti-clockwise. By right-hand grip rule, its magnetic field $\vec{B}_1$ points towards the observer (positive direction). Coil $C_3$ carries current clockwise. Its field $\vec{B}_3$ points away from the observer (negative direction). Initially, $C_2$ is midway. Since $C_1$ and $C_3$ are identical and carry equal current $I$, the fields at $C_2$ cancel: net flux $\Phi_{\text{initial}} = 0$. To induce a clockwise current in $C_2$, the induced field $\vec{B}_{\text{induced}}$ must point away from the observer (negative). So the external flux must be increasing in the positive direction (towards the observer). This is achieved by moving $C_1$ (source of positive flux) closer to $C_2$, and moving $C_3$ (source of negative flux) farther from $C_2$. Thus, $C_1$ moves towards $C_2$ and $C_3$ moves away from $C_2$. Answer:Option B: $C_1$ moves towards $C_2$ and $C_3$ moves away from $C_2$.