a
As rod moves in field area increases upto \(x=b\) then field is absent and again flux is generated on return journey from \(x=b\) to \(x=0\). Thus plot \(A\) for flux.
\(\Rightarrow e=-\frac{d \phi}{d t} \Rightarrow\) curve \(B\) for \(e m f\)
\(\Rightarrow\) Power dissipated \(=v i \Rightarrow\) curve \(C\) for power dissipated