4.6.1 Waves in air, fluids and solids

Question 1

What are transverse waves?

Answer 1

Waves that oscillate perpendicular to the direction of energy transfer of the waves.

Question 2

What are longitudinal waves?

Answer 2

Waves that oscillate parallel to the direction of energy transfer of the waves.

Question 3

What type of waves are sound waves?

Answer 3

Longitudinal

Question 4

What are mechanical waves?

Answer 4

Waves that need a medium to travel through

Question 5

What is the amplitude of a wave?

Answer 5

The maximum displacement of a point on the wave from its undisturbed position

Question 6

What is the period of a wave?

Answer 6

The time taken for each wave to pass a fixed point

Question 7

What is the wavelength of a wave?

Answer 7

The distance from one point on the wave to the equivalent point on the adjacent wave.

Question 8

What is the frequency of a wave?

Answer 8

The number of waves passing a fixed point per second.

Question 9

What is the wave speed?

Answer 9

The speed at which the energy is transferred (or the wave moves) through the medium.

Question 10

What unit is frequency measured in?

Answer 10

Hertz (Hz)

Question 11

Describe how ultrasound can be used in medical applications.

Answer 11

• Ultrasound waves have a frequency higher than the upper limit of hearing for humans.
• Ultrasound waves are partially reflected when they meet a boundary between two different media.
• The time taken for the reflections to reach a detector can be used to determine how far away such a boundary is.

Question 12

What are P - Waves

Answer 12

P-waves are longitudinal, seismic waves. P-waves travel at different speeds through solids and liquids.

Question 13

What are S waves?

Answer 13

S-waves are transverse, seismic waves. S-waves cannot travel through a liquid.

Question 14

What do P and S waves provide evidence for?

Answer 14

P-waves and S-waves provide evidence for the structure and size of the Earth’s core.

Question 15

What is echo sounding?

Answer 15

Using high frequency sound waves to detect objects in deep water and measure water depth.

Question 16

Explain how seismic waves provide evidence that the Earth has a liquid outer core.

Answer 16

S-waves can travel through liquids, but not solids.

S-waves are not detected on the opposite side of the Earth - this suggests that the mantle has solid properties, but the outer core must be liquid.

Question 17

Explain how seismic waves provide evidence that the Earth has a solid inner core.

Answer 17

P-waves can travel through both liquids and solids.

P-waves are detected on the opposite side of the Earth. Refractions between layers cause two shadow zones where no P-waves are detected. The size and positions of these shadow zones indicate there is a solid inner core.

Question 18

What is the normal range of human hearing?

Answer 18

20 Hz to 20,000 Hz

Question 19

Explain how we are able to hear noise of people talking loudly in another room

Answer 19

• Sound waves travel through the air and then through the walls
• The sound waves travel faster when going through walls as the wall is solid, meaning the particles are very close together
• The sound then travel through the air again and into our ears
• When they each your eardrums, the sound waves cause it to vibrate
• the vibration is transferred to small bones which send signals to your brain about what you are hearing