Physics 9702 · AS & A Level · Standard candles

Standard candles — practice question

Fig. 9.1 plots radiant flux intensity $F$ against $d^{-2}$ for star X, where $d$ is the observer's distance from the star. Fig. 9.2 plots the emission rate $P$ of radiation against wavelength $\lambda$ for star X and for the Sun. The Sun's surface temperature is 5770 K.
(a)[2]

State Wien’s displacement law in words.

(b)[3]

State three conclusions about star X that can be drawn from this data. The conclusions may be qualitative or quantitative. Use the space for any working.

(c)[2]

Star X is in a galaxy that is moving away from the Earth. Suggest, with a reason, how the line for star X in Fig. 9.2 would appear if it had been plotted from data measured on the Earth.

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This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: temperature is inversely related to wavelength

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