EXPERIMENTAL INVESTIGATION 30.5 What is the relationship between current and voltage?
Equipment Wires Power supply (battery of 6–12 V rating) Ammeter Voltmeter
SAFETY • Be careful of sharp ends on the wires.
• Do not set the power supply too high (check with your teacher before turning the circuit on).
Method
1. Set up the apparatus for the circuit shown in Fig. 30.20. Note: the ammeter is connected in series and the voltmeter is connected in parallel across the resistor.
2. Close the switch. 3. Adjust the variable resistor until the reading on the voltmeter is 1 V. 4. Record the reading on the ammeter when the voltage is at this setting.
5. Follow steps 3–4, increasing the voltage by 1 V each time. Record both voltage and current at each stage.
6. Record your results for the whole investigation. Draw a graph to represent these results with voltage on the y-axis and current on the x-axis.
Power supply Resistor
Bulb Switch Variable resistor Fixed resistor
Switch
Voltmeter Wires V
)Fig. 30.20 Circuit to show the relationship between current and voltage
A Ammeter j Go to page 94 of your Experimental Investigations Log to write up this investigation.