and the total current is I = = 9 A. (You could verify that 3 A of current
would flow in each of the three branches of the combination.) The power supplied
by the battery will be P = IV = (9 A)(90 V) = 810 W.
If the resistors are in series, the equivalent resistance is RS = 30 Ω + 30 Ω + 30 Ω
= 90 Ω, and the current drawn is only I = = 1A. The power supplied
by the battery in this case is just P = IV = (1 A)(90 V) = 90 W.
- A voltmeter is a device that’s used to measure the voltage
between two points in a circuit. An ammeter is used to measure
current. Determine the readings on the voltmeter (denoted )
and the ammeter (denoted ) in the circuit below.