Sound

• Physics
• Secondary Education

Light reaches the observer in 16 millionths of a second

The sound of thunder reaches the observer in about 15 seconds

Every 5 second difference equates to a distance of 1 mile

An observer, 3 miles away, sees a lightning flash about 15 seconds before hearing thunder

Choose appropriate words to fill in the gaps below:

Sound is a ___________ wave that in air consists of a series of compressions and _____________.

Sound travels fastest through _______ but does not travel at all through a __________.

A ____________ sound wave is called an echo. Sound also undergoes ___________.

On average, humans can hear sound frequencies from __________ to ____________.

rarefactions

refraction

vacuum

20 Hz

solids

longitudinal

reflected

20 000 Hz