P2 Topic 2: Controlling and using electric currents This topic looks at: How we measure current and voltage The relationship between voltage, current and resistance How the resistance of a circuit be changed How energy is transferred Draw a simple series circuit with an ammeter in place Draw a circuit with a voltmeter connected V = I × R what does this formula mean and what are the units? HIGHER what is potential difference and what are the units? P = I × V what does this formula mean and what are the units? Explain how changing the resistance in a circuit changes the current and how this can be achieved using a variable resistor Keywords: Current, ammeter, in series, series circuit, parallel circuit, voltmeter E = I × V × t what does this formula mean and what are the units? Draw and annotate how current varies with potential difference filament lamps Draw and annotate how current varies with potential difference diodes Draw and annotate current varies with potential difference for fixed resistors I V I V I V Keywords: potential difference, resistance, ohms, filament lamps, diodes, thermistors, LDR’s, power