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Answer ALL questions.

Write your answers in the spaces provided in this booklet.

1. (a) In this experiment, you will investigate the relationship between the peak-peak voltage of an
alternating current waveform and its effective value in delivering power to a pure resistor.
DO NOT WRITE IN THIS AREA
You are provided with the following:

• 20Ω, 100W wire wound resistor
• Calorimeter
• Mercury in glass thermometer (0ºC - 100ºC)
• Stirrer
• Large beaker containing approximately 1.5 litres water maintained at constant

temperature (ambient temp of tap water will suffice)
• Digital scale
• Oscilloscope
• 0-30V variable output voltage ac power supply (5A)
• Timer
• Calibrated digital multimeter

Procedure DO NOT WRITE IN THIS AREA
1. Weigh the empty calorimeter and record its weight in Table 1.
2. Pour approximately 200 mL of water into the calorimeter and weigh calorimeter and
the added water. Record this result in Table 1.
3. Determine, m, the mass of added water by subtraction and record this value in Table 1.
4. Using a calibrated multimeter, measure the true resistance, R, of the nominal 25Ω
resistor and record this value in Table 1.
5. Set up the apparatus as shown in Figure 1.

leads to DC circuit
thermometer stirrer

insulating
lid
heating element
air DO NOT WRITE IN THIS AREA

outer & inner liquid under
calorimeter test
Figure 1. Diagram of apparatus

The heating element is the 20Ω resistor and the leads will be connected to the AC supply
(instead of DC as shown in the diagram).
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