Q95 · Practice questionComplex unfamiliar6 marks
QUESTION 95 (6 marks)
A star can be approximated as a blackbody with peak wavelength . A metal surface has work function . Determine (a) the star’s approximate surface temperature, (b) the energy in eV of a photon at the peak wavelength and (c) whether a peak-wavelength photon can eject an electron from the metal.
WORKED SOLUTION
6 marksPractice marking scheme
ANSWER
; ; no photoelectron is emitted by a single peak-wavelength photon.
Worked solution
Wien’s law:
Photon energy:
Convert to eV:
Because , the photon energy is below the work function, so that photon cannot eject an electron.
Applies Wien’s law.
Calculates temperature.
Calculates photon energy in joules.
Converts photon energy to eV.
Compares with work function.
States correct photoelectric conclusion.
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