Question

In the figure, two straight conducting rails form a right angle. A conducting bar in contact with the rails starts at the vertex at time $t=0$ and moves with a constant velocity of $v$ along them. A magnetic field $B$ is directed out of the page. The current in the loop is $\left(\right.\lambda =$ resistance per unit length of the rails and bar).

• A. $\frac{2 B v}{\lambda }$
• B. $\frac{B v}{\lambda \left(1 + \sqrt{2}\right)}$
• C. $\frac{\sqrt{2} B v}{\lambda }$
• D. $\frac{2 B v}{\lambda \left(1 + \sqrt{2}\right)}$

Answer 1

Answer: (B)

$EMF=\frac{d}{d t}\left(B v t \times v t\right)=2Bv^{2}t$
and resistance $=\lambda \left(2 v t + 2 \sqrt{2} v t\right)$