Waves

Question 1

What is the frequency of waves and how is it measures?

Answer 1

It is the number of waves that pass a point each second. It is measured in Hz.

Question 2

How do the particles in longitudinal waves travel? Give an example

Answer 2

They move back and forth ALONG the direction of wave travel. Example: sound waves

Question 3

How do the particles in transverse waves travel? Give an example

Answer 3

They move at right angles to the direction of wave travel. Example: electromagnetic waves

Question 4

If a wave has a frequency of 10Hz and wave length of 2m, what is its speed?

Answer 4

20m/s

FREQ x WAVE LENGTH

Question 5

How are sound waves transmitted and reflected through materials?

Answer 5

Transmitted when the densities are similar. Reflected when there is a big difference in the densities of materials .

Question 6

State 4 things that can happen to a wave at a boundary between two materials

Answer 6

The waves can be reflected (bounces back at surface), refracted (passes through but at a changed speed), transmitted (wave energy is transferred) or absorbed (wave energy transferred into a thermal energy store)

Question 7

How are sound waves produced?

Answer 7

When an object vibrates it produces oscillations that transfer energy from the source to the ear

Question 8

How does the ear detect sound?

Answer 8

Sound waves travel down the ear canal and cause the ear drum to vibrate. These vibrations are then converted to an electrical signal and are carried to the brain

Question 9

Describe infrasound and where it is found

Answer 9

Infrasound is sound waves with a frequency below 20Hz. It travels through the earth as shockwaves from tsunamis, volcanoes and earthquakes

Question 10

Describe ultrasound and its uses

Answer 10

Sound waves with a frequency above 20kHz. Used to make images inside the body.
Waves sent to the body, and some of the waves are reflected whenever they reach tissue with a different density to the one it just passed through. Computer detects echos and makes an image

Question 11

Why can the human ear only detect sound in the range from 20Hz to 20000Hz?

Answer 11

Sound waves in the air are converted into vibrations and pass through the ear. This conversion of waves to vibrations can only happen in this range of frequencies.

Question 12

How does the density of a material affect the speed of sound in the material?

Answer 12

The greater density, the greater speed, as the wave can be passed more easily from particle to particle (since they are more tightly packed)