1. An electrical circuit contains a cell or battery with FEM ₀ , and a resistor with resistance R, length l and mass m, which can freely move laterally, as indicated in the following figure. As illustrated, there is a uniform magnetic field B perpendicular to the plane of the circuit. When switch S is closed, the current in R can be assumed to be /R at t = 0. Show that the induced current is given by i_ind = l² /B²t/(mR²)under condition that t is not too large. I indicated what happens for a large value of t.