Q. A conductor AB of length l moves in x-y plane with velocity $ \displaystyle \vec{v} = v_0(\hat{i}-\hat{j})$ . A magnetic field $\displaystyle \vec{B} = B_0(\hat{i}+\hat{j})$ exists in the region. The induced emf is
(a) zero
(b) 2B0lv0
(c) B0lv0
(d) √2 B0lv0
Ans: (a)
Sol: Since velocity & magnetic field are in X-Y Plane , hence their vector Product is Perpendicular to X-Y plane .
Since $\displaystyle (\vec{v}\times \vec{B})$ is Perpendicular to $\displaystyle \vec{l}$
$ \displaystyle \vec{l}.(\vec{v}\times \vec{B}) = 0 $
Induced emf , $\displaystyle E = \vec{l}.(\vec{v}\times \vec{B})$
E = 0