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**1. Homework Statement**

Assume that a metal bar of length h and mass m can slide on a rail without friction. The rail completes the circuit through a capacitor of capacitance C. There ia a uniform magnetic field of magnitude B, perpendicular to the plane of the circuit. Assume the resistance of the circuit is negligible, and initially the bar is moving with velocity v. Find the velocity and position of the bar as a function of time. (You can also solve this problem if the resistance of the circuit is R, it is not more complicated.)

[On the paper, B is given with a circle with a dot at the center, so it points inwards through the paper.]

**3. The Attempt at a Solution**

The time derivative of the flux through the circuit is hv, and I know that this is the emf of the moving bar. Also, the force on the bar h.I.B. So, I need to find the current and substitute it in F=ma -> h.B.I = m.(dv/dt) to find v(t), and integrate it to find x(t)... But my problem is that I can't find the current through a capacitor with an applied emf of hv.