Figure 5 shows the arrangement used by Fizeau to determine the speed of light - AQA - A-Level Physics - Question 3 - 2022 - Paper 7

To determine if the speed of light can be measured, we first calculate the maximum measurable speed using the formula:

$2 = S \times 10^8 \text{ m s}^{-1}$

By calculating the value of d (where d = 8.5 km = 8500 m) and substituting:

1. Calculate the time for light to travel to the mirror and back:
   • Time taken $t = \frac{2d}{c} = \frac{2 \times 8500}{3 \times 10^8}$
   • Maximum teeth rotation at 620 rev/min gives:
   • $f = \frac{720 \times 620}{60}$
   • This value of frequency will be compared with the calculated speed.
2. Conclusion: The largest possible speed measured is less than the speed of light if the calculated maximum does not exceed $c$.

$\epsilon_0$ is related to the electric field strength in free space, which is charged. $\mu_0$ relates to the magnetic field strength in a vacuum. In other words, $\epsilon_0$ is linked to the ability to carry electric fields, while $\mu_0$ is associated with the magnetic field under dynamic conditions.