An electromagnetic wave of frequency 6 × 1014 Hz propagating in vacuum has a momentum of ________.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → ~1.32 × 10−27 kg ms−1
Electromagnetic waves carry momentum as well as energy. Since only the frequency is given, the question asks for the momentum of one photon of this wave.
\( \displaystyle p = \frac{E}{c} = \frac{h\nu}{c} \)
\( \displaystyle p = \frac{6.63\times10^{-34} \times 6\times10^{14}}{3\times10^{8}} \)
\( \displaystyle p \approx 1.32\times10^{-27}\,\mathrm{kg\,m\,s^{-1}} \)