Level 1: Magnet Into a Coil, Fast vs Slow: Which Sends More Charge?
Is the heat the same too?
A magnet is pushed into a coil of resistance R in 0.1 s, and then, from the same start, in 1 s. In each push the flux changes at a steady rate, and the same charge flows. The heat produced in the coil in the 0.1 s push is:
With a steady rate of flux change, the current is constant during each push and equals the charge divided by the time taken. The heat is the current squared, times the resistance, times the time.
The same charge pushed through in a tenth of the time produces ten times the heat. The quicker push is harder work: the extra energy you supply against the magnetic braking becomes heat in the coil.
Every Level 2 starts from a quick question, Level 1, and changes one thing. Seeing what that change does is the skill JEE Main tests. Try it here, free and with no signup, then read the worked answer.
