The Speed of Light – Practice


1) If Galileo had his assistant stand 2km away when he attempted to measure the speed of light with lamps, what time would he have recorded if he was to accurately measure the speed of light?

2) If Fizeau was to conduct his experiment by reflecting a light beam from a surface 19km away, how many times per second would the disc need to rotate if it had a radius of 20cm and the teeth were 1mm wide in order to block the returning light beam?

Quick Answers:

1) 1.3 × 10-5 s

2) 6.28 rotations per second

Worked Answers: