## anonymous 4 years ago An electric clothes dryer draws 18 A from a 240-V wall outlet How much power in watts does it use?

1. anonymous

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

2. JamesJ

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 $P = VI$

3. anonymous

so 4320?

4. anonymous

or convert to watts?!?

5. JamesJ

4,320 Watts, yes.

6. anonymous

oh ok

7. JamesJ

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

8. anonymous

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