1. Do now: The AC supply voltage shown is applied across a 1kΩ resistor. Tūrei, 15 Mahuru 2015 Calculate: 1) The frequency of the AC supply 2) The peak current 2) The peak current 3) The maximum power output 3) The maximum power output Sketch: 4) The graph of current vs time 5) Power vs time 5) Power vs time

2. Tūrei, 15 Mahuru 2015 Homework: Set 1 & 2 should be finished Set 3 (inductors) due 18 Sep Mid-unit Test: Wednesday 18 th September (P3) Kirchoff and internal resistance Capacitors & inductors

3. LO21: Define RMS voltage (current and power) in terms of their peak values in terms of their peak values Today’s Kaupapa:

5. The RMS value is usually quoted, not the peak value, and can be compared to the DC values (same power) AC VoltageDC Voltage (with same power output) V rms V max (See text pg 263-264 for derivations of these formulae)

6. Example: The household power supply in NZ is 240V AC at 50Hz a)Find the peak voltage of the household supply b)Sketch a graph of voltage vs time for 1 cycle (with appropriate values and labels on the axes) c) Find the peak and RMS value of the current in a 100W light bulb connected to the household supply

7. Do Activity 16A