Lenz's Law is said to be a consequence of the principle of conservation of energy. Explain this statement by describing what would happen if Lenz's Law were reversed. Take the example of a wire loop with a changing magnetic flux, and describe what would happen if current were induced opposite to the way it really is.

Let's say you take an ordinary wire coathanger and straighten out the hook shaped part that normally hangs over the coatrack. Now, you can spin the (roughly) triangular part around by twisting the straightened part between your fingers. Estimate the EMF that you can generate by spinning the hanger in the Earth's magnetic field (about 5 x 10^-5 T).

Here's one way of understanding a capacitor: It is a device that won't let the voltage between two points change too rapidly, because it stores up charge and has V = Q/C. The charge cannot be changed instantaneously, so the voltage cannot either.

Please describe an inductor in a similar way, that is, say what cannot be changed rapidly and why.

Estimate the inductance of a solenoid made by buying a typical spool of wire from hardware store and winding it carefully around a broom handle.

A wire hoop (shown in blue) surrounds a long solenoid. If the current in the solenoid increases, will there be any current induced in the loop? If so, which way will the current flow?

A car battery has an emf of only 12 V, yet energy from the battery provides the 20,000 V spark that ignites the gasoline. How is this possible?