Self Test on Tutorial 10 
For the mains, the potential difference changes direction with a frequency of . Hz
This means that one complete cycle takes time T =
The potential difference is given as .. V. In fact the peak p.d., V_{0}_{}, is more like 325V
Label the two axes with the quantities that can be measured with the CRO
The average p.d would be . but this is not very useful energy is obviously being transferred so, to get some idea of an average, it is useful to look at the power delivered.
Heating effect Power P = IV =
For the peak current, I_{0} =
If I = 0, power =
The mean power =
Show these quantities on the axes
The root mean square value of I for a.c. I_{rms}, is the current (dc) that would give the same power as the mean (ac) power
I_{rms }^{2} =
I_{rms } =
Also V_{rms} = eg for the mains, V_{0 } = 325 V so V_{rms} =
