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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 part of the investigation. Describe how t... 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 use a thermometer or a temperature sensor to measure the temperature of the water in the copper container.
Data should be collected at regular time intervals, such as every minute, to monitor the cooling process over a specific duration. Alternatively, they can use a datalogger for precise readings. This method enables the student to record initial temperature and subsequent readings over time, allowing for the calculation of the cooling rate.
Step 2
Describe how the intensity of the radiation varies with wavelength in Figure 10.
Answer
The intensity of the radiation emitted by the halogen lamp varies with wavelength in a characteristic manner. As shown in Figure 10, the intensity reaches a peak value at a specific wavelength related to visible light, indicating that the lamp emits the most radiation at this point. Furthermore, the radiation intensity decreases on both sides of this peak, demonstrating that shorter and longer wavelengths have less intensity.
Step 3
Calculate the gradient of the graph at a time of 30 ms.
Answer
To calculate the gradient at 30 ms, we need to draw a tangent to the curve at that point, identifying coordinates on the graph. For instance, if the tangent intersects the temperature axis at 80°C and the time axis at 20 ms and 40 ms, we can derive the gradient using the formula:
ext{Gradient} = rac{ ext{change in temperature}}{ ext{change in time}} = rac{80 - 60}{40 - 20} = 1.0 ext{°C/ms}
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 due to the conversion of electrical energy into thermal energy as it operates. Initially, the heat generated causes a significant temperature increase. Once the halogen lamp reaches its operating temperature, the heat loss to the environment balances the heat generated, resulting in a steady-state condition where the temperature remains constant.