Misc: A device used to change the voltage of alternating currents is a ______.?

Questions

who directed the monochrome sequences at the beginning & end of "the wizard of oz" (1939)?

who directed top gun?

who does the voice for homer on the simpsons?

who finds a tiny flying saucer on her roof in "the invaders"?

who had one of his nipples bitten off by an alligator while he was host of his wild kingdom show?