This apparatus shows a resistor in some water. A student measures the rise in temperature of

This apparatus shows a resistor in some water.

A student measures the rise in temperature θ of the water in 100 s using two different values of voltage.
The student wrote:
‘When the voltage was set at 6.0 V, the rise in temperature of the water in 100 s was 14.5 °C. The voltmeter reading decreased by about 0.2 V during the experiment, and so the final voltmeter reading was 5.8 V.
‘The reading fluctuated from time to time by about 0.2 V. The smallest scale division on the thermometer was 1 °C, but I could read it to 0.5 °C. I did not have time to repeat the reading.
‘When the voltage was set at 12.0 V, the rise in temperature in 100 s was 51.0 °C and the voltage was almost the same at the end, but fluctuated by about 0.2 V.’
a. Estimate the percentage uncertainty in the measurement of the first voltage.
b. It is suggested that θ is related to V according to the formula θ = kV², where k is a constant.
i. Calculate two values for k. Include the units in your answer.
ii. Justify the number of significant figures you have given for your value of k.
iii. Explain whether the results support the suggested relationship.
c. Describe four sources of uncertainty or limitations of the procedure for this experiment.
d. Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.

Transcribed Image Text:

variable power supply V crocodile clips beaker water resistor Figure P1.23