A Christmas carousel changes what energy into what

The carousel's own rotational movement generates power, which is transformed into electricity to power the merry-go-round, which also includes safety lights for playing when the sun has set. It is intended for children over 10 years old and can rotate three at a time.

The time constant is how long will the current decrease by 1/e. The numerical value of this is approximately equal to 0.37. Since we are looking at the decrease which is equal to 1 less than this value, the answer would be 0.63. Thus, the answer to this item is letter E.