An experimental setup is used to investigate the polarization of electromagnetic waves. A microwave transmitter emits vertically polarized microwaves. A receiver with a dipole antenna is used to detect the signal, and an oscilloscope displays the amplitude of the detected signal. Initially, the dipole receiver is oriented horizontally, perpendicular to the polarization of the transmitter, so that the detected amplitude is zero. The receiver is then rotated in a plane perpendicular to the direction of wave propagation through a full 360∘360^\circ360∘ rotation.
Sketch a graph to show how the detected amplitude of the signal varies with the angle of rotation as the receiver is rotated from 0∘0^\circ0∘ to 360∘360^\circ360∘. Start your graph from the initial perpendicular position (0∘0^\circ0∘).
Maxwell derived the equation
c=1μ0ε0 c = \frac{1}{\sqrt{\mu_0 \varepsilon_0}} c=μ0ε01for the speed ccc of electromagnetic waves, where μ0\mu_0μ0 is the permeability of free space and ε0\varepsilon_0ε0 is the permittivity of free space. Given that μ0=4π×10−7 H m−1\mu_0 = 4\pi \times 10^{-7} \text{ H m}^{-1}μ0=4π×10−7 H m−1 and ε0=8.85×10−12 F m−1\varepsilon_0 = 8.85 \times 10^{-12} \text{ F m}^{-1}ε0=8.85×10−12 F m−1, calculate the speed predicted by this equation and explain how this result led to the conclusion that light is an electromagnetic wave.
26 exam-style questions on AQA A Level Physics Wave-particle duality (A-level only), covering Newton's corpuscular theory of light (A-level only), Significance of Young's double slits experiment (A-level only), Electromagnetic waves (A-level only), The discovery of photoelectricity (A-level only), Wave-particle duality (A-level only), and Electron microscopes (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.