Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A rod m long slides at m/s along two rails in a field of T, at right angles to the field. The rails are joined by a resistor, and the whole circuit has a resistance of . Find the emf, the current, the force on the rod, and the power that must be supplied to keep it moving.
A conductor of length moving at speed across a field has . In a circuit of resistance the current is and the force on the rod is , always against the motion. The charge that flows is . A capacitor in the circuit adds a mass .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. m, m/s, T, .
Step 1. The emf. .
Step 2. The current. .
Step 3. The force. . It acts against the motion, so the pull must be N along the motion.
Step 4. The power. .
Answer: V, A, N and W.
Check. The heating power is . It equals the power supplied.
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