A transformer is a device used to

increase or decrease an ac voltage.

transform an alternating current into a direct current.

transform a direct current into an alternating current.

increase or decrease a dc voltage.

Question $3$

$6\mathrm{.}67$ pts

A resistor and an inductor are connected in series to a battery. The time constant for the circuit represents the time required for the current to reach

$75\%$ of the maximum current.

$63\%$ of the maximum current.

$37\%$ of the maximum current.

$25\%$ of the maximum current.