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a) A student investigates how different surfaces radiate energy as they cool - Edexcel - GCSE Physics - Question 8 - 2018 - Paper 1
Question 8
a) A student investigates how different surfaces radiate energy as they cool. Figure 9 shows some of the apparatus used in a part of the investigation. Describe ho... show full transcript
Worked Solution & Example Answer:a) A student investigates how different surfaces radiate energy as they cool - Edexcel - GCSE Physics - Question 8 - 2018 - Paper 1
Step 1
Describe how the student could collect data to show how the rate of cooling of the container and water change with time.
Answer
The student can measure the temperature of the water in the copper container using a thermometer or a temperature sensor. They should record the temperature at regular intervals, such as every minute, to create a time series of data. This allows for the observation of cooling trends over time and helps determine the rate of temperature change.
Step 2
Describe how the intensity of the radiation varies with wavelength in Figure 10.
Answer
In Figure 10, the graph shows that the intensity of the radiation emitted by the halogen lamp peaks at a specific wavelength, indicating that the maximum intensity occurs at this point. As the wavelength increases or decreases from this peak, the intensity decreases, showing that there is a range of wavelengths over which the intensity is significant but declines on either side of the peak.
Step 3
Calculate the gradient of the graph at a time of 30 ms. State the unit.
Answer
To calculate the gradient at 30 ms, a tangent must be drawn between 20 ms and 40 ms on the graph, and the change in temperature should be divided by the change in time. For instance, if the temperature at 20 ms is 130°C and at 40 ms is 200°C, the gradient would be:
The unit for the gradient is °C/ms.
Step 4
Explain why the temperature of the lamp rises and then remains at a constant value.
Answer
The temperature of the lamp rises initially because the halogen lamp produces heat as electrical energy is converted to light energy. This increase continues until the lamp reaches a steady state where the heat generated is equal to the heat lost to the environment. Once this equilibrium is achieved, the temperature remains constant despite the continuous operation of the lamp.