An experimental setup is used to investigate the polarization of electromagnetic waves.
A UHF transmitter emits horizontally polarized radio waves. A receiving dipole antenna is connected to an oscilloscope to measure the detected signal amplitude. Initially, the dipole antenna is aligned horizontally, parallel to the polarization of the transmitter, so that the detected amplitude is at its maximum. The receiving antenna is then rotated in a plane perpendicular to the direction of wave propagation through a full 360∘ 360^\circ\,360∘ rotation.
Sketch a graph to show how the magnitude of the detected signal amplitude varies with the angle of rotation as the receiver is rotated from 0∘ 0^\circ\,0∘ to 360∘360^\circ360∘. Start your graph from the initial parallel position (0∘0^\circ0∘).
Maxwell's electromagnetic theory predicts that the speed c c\,c of electromagnetic waves in a vacuum is related to the permeability of free space μ0 \mu_0\,μ0 and the permittivity of free space ε0 \varepsilon_0\,ε0 by the equation:
c=1μ0ε0 c = \frac{1}{\sqrt{\mu_0 \varepsilon_0}} c=μ0ε01Given that the experimentally measured speed of light is c=2.998×108 m s−1c = 2.998 \times 10^8 \text{ m s}^{-1}c=2.998×108 m s−1 and the permeability of free space is 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:
