Properties of Waves including Light and Sound

Question 1

How does sound travel through solids? What type of waves are sound waves? Can sound travel through a vacuum?

Answer 1

Sound waves cause vibrations through the solid.

Sound waves are longitudinal waves.

Sound cannot travel through a vacuum, it requires a medium to be transmitted.

Question 2

What is an echo?

Answer 2

A reflected sound wave.

Question 3

How can the speed of sound be measured?

Answer 3

• Fire a pistol at a known distance
  from a solid wall.
• Record the time taken for the echo
  to be heard.
• Half the time and use
  speed = distance/time
  to calculate speed.

Question 4

What is the speed of sound in air?

What is the speed of sound in steel?

Answer 4

343 m/s

5130 m/s

Question 5

How does the speed of sound compare in solids, liquids and gases?

Answer 5

It’s the fastest in solids and slowest in gases.

Question 6

What is the range of frequencies audible to the human ear?

Answer 6

20 Hz - 20KhZ

20 - 20,000Hz

Question 7

What is ultrasound? Describe the applications.

Answer 7

Sound with a frequency higher than 20kHz.

Ultrasound is used largely in medical imaging, specifically pregnancy scanning as it is non-ionizing so it doesn’t increase the risk of cancer.

Question 8

What is a longitudinal wave.

Answer 8

A wave where the oscillations are parallel to the direct of motion.

Question 9

Describe the features of a longitudinal wave.

Examples.

Answer 9

Longitudinal waves have compressions and rarefactions.

E.g. Pulses along a spring, sound waves, ultrasound

Question 10

What wave property affects the volume of sound?

Answer 10

The amplitude ( greater amplitude = louder sound ).

Question 11

What wave property affects the pitch of sound?

Answer 11

The frequency ( higher frequency = higher pitch ).

Question 12

What is SONAR imaging?

Answer 12

SONAR ( Sound Navigation and Ranging ) uses both low and high frequency sound waves for imaging eg. underwater.

Question 13

What is a wave?

Answer 13

A regular disturbance transferring energy in the direction of the wave’s propagation without transferring matter.

Question 14

What is a transverse wave? Give examples.

Answer 14

A wave in which oscillations are at right angles ( perpendicular ) to the direction of motion.

Waves on a string, all electromagnetic waves, ripples on water, vibrations on guitar strings.

Question 15

Transverse waveforms have…

Answer 15

peaks and troughs.

Question 16

Longitudinal waveforms have…

Answer 16

Compressions and rarefactions.

Question 17

Wavelength is..

Answer 17

the shortest distance between the same point on two consecutive waves.

Question 18

Displacement is…

Answer 18

• The distance from equilibrium position.

- At maximum distance, this is amplitude.

Question 19

Frequency is..

Answer 19

the number of complete waves passing a given point per second, or the number of waves per second produced by the source.

Question 20

Wave equation

Answer 20

v = λ x f

v = velocity ( m/s )
λ = wavelength ( m )
f = frequency ( Hz )

Question 21

What is refraction?

Answer 21

Refraction is the change in speed of a wave when crossing a boundary between two media, resulting in a change in direction.

Question 22

What property of a wave is not changed by refraction?

Answer 22

The frequency.

Question 23

What happens when waves are incident on a flat surface?

Answer 23

Reflection.