An offshore research vessel sends a radio signal to a shore station. The signal has a wavelength of 0.75 m and travels at 3.0×108 m s−13.0\times10^8\ \mathrm{m\,s^{-1}}3.0×108 ms−1. The transmitting circuit makes 3.2 × 106 complete oscillations before the signal is switched off.
How long does the signal last?
Use v=fλv=f\lambdav=fλ.
0.014 s0.014\ \mathrm{s}0.014 s
1.3×102 s1.3\times10^2\ \mathrm{s}1.3×102 s
0.0080 s0.0080\ \mathrm{s}0.0080 s
0.011 s0.011\ \mathrm{s}0.011 s
104 exam-style questions on Edexcel GCSE Physics 5.4 Uses and dangers of EM radiation, covering 5.4.1 Dangers of electromagnetic radiation, 5.4.2 Uses of electromagnetic radiation, 5.4.3 Radio waves and oscillations in circuits, and 5.4.4 Changes in atoms and nuclei generating radiation. Each one has a worked solution and a mark scheme showing where the marks go.