CAIE A-Level Physics A2 22.1.3 E Hf Questions

Practise using E = hf and c = fλ to calculate photon energy, frequency or wavelength, with consistent units and rearrangement.

Exam points

calculate photon energy using E = hf
rearrange E = hf to determine frequency or Planck constant and use consistent units

[Maximum number: 2]

Fig． 8.1 shows part of the emission spectrum of visible radiation emitted by hydrogen gas in a star in a distant galaxy．

Fig． 8.1

The galaxy is moving away from the Earth at a speed of $6.2 \times 10^{6} \mathrm{~ms}^{-1}$ ．

Calculate the energy of a photon of this radiation．

photon energy =J [2]

E=h f and $\lambda=c / f$ $\begin{aligned} E =\left(6.63 \times 10^{-34} \times 3.00 \times 10^{8}\right) /\left(488 \times 10^{-9}\right) =4.08 \times 10^{-19} \mathrm{~J} \end{aligned}$

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CAIE A-Level Physics A2 22.1.3 E Hf Questions question 1