# A.C. Circuit

1. May 2, 2006

### frozen7

An electric toaster draws 3A rms current from a 240V, 50Hz source. Calculate the average power and peak value of the instantaneous power to the toaster.

$$P(average) = I (rms) x V (rms) cos \phi$$

Since the power factor is not mentioned in the question. Can the question be solved?

2. May 2, 2006

### Staff: Mentor

If the power factor isn't given, it probably isn't needed. What would you guess the power factor of a toaster to be? What is the heating mechanism?

3. May 2, 2006

### frozen7

Is it because all the energy become heat so the power factor is equal to one ?

4. May 2, 2006

### Staff: Mentor

Yeah. The heating element is purely resistive, and the power factor of a resistive circuit is unity. You only get a phase shift between the applied voltage and resulting current if the load is reactive.