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The graphs show how the radiation per unit surface area, R, varies with the wavelength, λ, of the emitted radiation for two stars, P and Q - Scottish Highers Physics - Question 7 - 2016
Question 7
The graphs show how the radiation per unit surface area, R, varies with the wavelength, λ, of the emitted radiation for two stars, P and Q. A student makes the foll... show full transcript
Worked Solution & Example Answer:The graphs show how the radiation per unit surface area, R, varies with the wavelength, λ, of the emitted radiation for two stars, P and Q - Scottish Highers Physics - Question 7 - 2016
Step 1
I Star P is hotter than star Q.
Answer
To determine if Star P is hotter than Star Q, we can observe the peak of the emitted radiation curves. The peak wavelength of radiation emitted is inversely related to temperature according to Wien's Law. If the peak for Star P occurs at a shorter wavelength than that of Star Q, this indicates that Star P is hotter. This appears to be true from the graph.
Step 2
II Star P emits more radiation per unit surface area than star Q.
Answer
Examining the area under the curve (R vs λ) for Star P compared to Star Q, we can see that Star P has a greater value of R across a wider range of wavelengths. Therefore, this statement is also true, as Star P emits more radiation per unit surface area than Star Q.
Step 3
III The peak intensity of the radiation from star Q is at a shorter wavelength than that from star P.
Answer
This statement is false. The graph indicates that Star Q has its peak intensity at a longer wavelength than Star P. Thus, Star Q does not emit peak radiation at a shorter wavelength.