In a thunderstorm, both light and sound waves are generated at the same time.

a. How fast does the light travel towards an observer?

b. Explain why the sound waves always reach the observer after the light waves.

c. The speed of sound waves in air may be determined by experiment using a source that generates light waves and sound waves at the same time.

i. Draw a labelled diagram of the arrangement of suitable apparatus for the experiment.

ii. State the readings you would take.

iii. Explain how you would calculate the speed of sound in air from your readings.