Question

An electric clothes dryer draws 18 A from a 240-V wall outlet How much power in watts does it use?

Answer 1

W = A x V.... so 4320?

Answer 2

Power is the rate of change of work. The amount of work moving a charge C over a potential difference V is

W = VC

Now the rate of change of work where V is constant is

\[ Power = P = V \frac{\Delta C}{\Delta t} = V I \]
where \( I \) is current. By definition current is the rate at which charge moves.

Hence to find the power of this circuit, calculate

\[ P = VI \]

Answer 3

so 4320?

Answer 4

or convert to watts?!?

Answer 5

4,320 Watts, yes.

Answer 6

oh ok

Answer 7

Watt = Joule/sec

hence it must be that VC has units Joules. Its a good exercise to understand why that is the case.

Answer 8

ahh what about, "In a __________ circuit, the voltage across all resistors is the same."

Answer 9

Parallel