Question

A triangle is made of conducting rods. The triangle is released from rest in a vertical plane. If the triangle enters completely into the magnetic field in time t, then the possible answer of t is

• A. t = 1 s
• B. t = 0.3 s
• C. t = 1.7 s
• D. t = 0.8 s

Answer 1

The correct option is C t = 1.7 s

Say there is no magnetic field, then
$5=\frac{1}{2}g{t}^2\Rightarrow t=1s$

From to Lenz’s law, the motion of the triangle is opposed; hence, time required to cover 5 metre is greater than 1 sec.