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This circuit consists of an AC source and a resistor. An oscilloscope records the potential difference across a resistor RS and the current flowing through it. This information is shown in the graph from the oscilloscope below. RO 20 60 15 40 10 20 5 Current Potential difference through 0 across resistor 0.005 0.01- 0.015 0.02 the resistor (mA) (Volts) Time (seconds) 5 -20 -10 .40 -15 -20 60 - Current (mA) . Voltage across resistor a) Find the frequency of the AC source. b) Find VPEAK across the resistor as measured by the oscilloscope. c) Calculate the value of VRMS across the resistor. d) Calculate the value of R, the resistance of the resistor in Q. e) Explain, sketching a diagram if necessary, why it is important that household appliances with a metal case have it earthed