Question

A 1500-W electric heater is plugged into the outlet of a 120-V circuit that has a 20-A circuit breaker. You plug an electric hair dryer into the same outlet. The hair dryer has power settings of 600 W, 900 W, 1200 W, and 1500 W. You start with the hair dryer on the 600-W setting and increase the power setting until the circuit breaker trips. Under what setting does the circuit breaker trip.

Answer 1

P=900W

Step-by-step explanation:

We need to define a variable, where the system can be used without tripping the circuit.

So we define,

`P_(A) = VI`

Making the substitution for
`V=120V` and
`I=20A`, we can find
`P_(A)`,

`P_(A) = (120V)(20A)\\P_(A) = 2400W`

We know as well that the power required to operate is 1500W(P_{B}, so

P=P_{A}-P_{B}

Making the substitution for the values we have,

`P=2400W-1500W\\P=900W`

So we found the power setting at which the circuit breaker trips.