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A student is investigating the refraction of light - Edexcel - GCSE Physics - Question 5 - 2021 - Paper 1
Question 5
A student is investigating the refraction of light. Figure 5 shows part of the apparatus and the angles to be measured. The student measures angle r for several dif... show full transcript
Worked Solution & Example Answer:A student is investigating the refraction of light - Edexcel - GCSE Physics - Question 5 - 2021 - Paper 1
Step 1
On the graph in Figure 6, draw the best fit curve.
Answer
To draw the best fit curve, sketch a smooth line that passes through the origin and closely follows the trend of the plotted points on the graph. Ensure that the curve captures the relationship between angle i and angle r displayed by the data.
Step 2
Use the graph in Figure 6 to estimate the value of angle r when angle i is 80°.
Answer
Using the graph, locate the point where angle i is 80° on the horizontal axis. Draw a vertical line up to intersect the best fit curve, then draw a horizontal line to the left to read off the corresponding angle r on the vertical axis. The estimated value of angle r is approximately 42° ± 2°.
Step 3
Describe how angle r changes with angle i for the results shown on the graph in Figure 6.
Answer
As angle i increases, angle r also increases. However, this increase is not proportional, meaning that angle r increases at a decreasing rate for the same increase in angle i. Thus, angle r remains consistently less than angle i.
Step 4
Explain the decrease in intensity as the light travels from P to Q.
Answer
As light travels from P to Q through the glass block, the intensity decreases due to absorption and scattering within the glass material. The surface of the glass can also reflect some of the light, leading to a lower intensity at Q compared to P. It is important to note that the light is still refracted, contributing to the observed decrease.
Step 5
Which of these sketch graphs represents the speed of light as it travels from P to Q?
Answer
The correct sketch graph will show that the speed of light decreases as it enters the glass block from air (at P) and continues at a lower speed while in the glass (at Q). This indicates that the speed of light in air is greater than that in glass.