SP4- Waves

Question 1

Transverse waves

Answer 1

• particles move up and down at right angles to direction the wave is moving.
• particles not carried along with the wave.
• (e.g sea waves, light waves)

Question 2

Longitudinal waves

Answer 2

• particles move back and forth in same direction as wave is traveling.
• (e.g sound waves)

Question 3

Electromagnetic waves

Answer 3

• transverse wave.

- do not need a medium (material) through which to travel.

Question 4

Frequency

Answer 4

• number of waves passing a point each second.
• measured in Hertz (Hz).
• 1 Hz = 1 wave passing per second.

Question 5

Period

Answer 5

• length of time it takes one wave to pass a given point.

Question 6

Wavelength

Answer 6

• distance from a point on one wave to point in the same position on next wave.
• measured in Metres (M).

Question 7

Amplitude

Answer 7

• maximum distance of the point on the wave away from its rest position.
• measured in Metres (M).
• greater amplitude of sound wave = louder the sound.

Question 8

Velocity

Answer 8

• speed of wave in the direction its travelling.

Question 9

Wave speeds

Answer 9

• speed (m/s) = distance (m) / time (s)

- wavespeed (m/s) = frequency (Hz) X wavelength (m)

Question 10

Refraction

Answer 10

• refraction happens at INTERFACE (boundary) between the two media.
• line at right angles to the interface = NORMAL LINE
• light travelling along normal line DOES NOT refract.
• light refracts TOWARDS the normal when SLOWS down
• light refracts AWAY from the normal when SPEEDS up

Question 11

How does change in speed of a wave affect its direction?

Answer 11

• bend of refraction depends on
  . how fast light travels into the two media
  . angle of light hitting the interface.
• greater the difference inspeed

Question 12

Transmitted

Answer 12

• wave passes through the material and is not absorbed or transmitted.

Question 13

Absorbed

Answer 13

• Wave disappears as the energy it is carrying is transferred to the material.

Question 14

Why can a prism be used to split up visible light into the colours of the rainbow?

Answer 14

• colours in light change speed by different amounts when transferred from air to glass = refracted through varying angles.

Question 15

Sound wave passes a gas or liquid

Answer 15

• particles vibrate backwards and forwards

Question 16

Sound waves passes a solid

Answer 16

• some of energy it’s transferring is reflected
• some energy is transmitted through solid or absorbed
• sound wave causes change in pressure on surface = causes particles to vibrate = disturbance is passed from air to solid

Question 17

Human Ear - internal structure as sound wave passes through

Answer 17

1) sound wave enters ear canal
2) sound wave vibrates ear drum
3) vibrations passed on to tiny bones which amplify
4) vibrations passed on to liquid inside cochlea
5) hairs inside cochlea detect vibrations - create impulses
6) impulses travel along neurones in the auditory nerve to reach brain

Question 18

How does the cochlea work?

Answer 18

• coiled tube containing liquid
• detects different frequencies (20hz - 20000hz)
• membrane in middle of tube is thicker and stiffer at base and thinner at apex
• part that vibrates depends on frequency
• hairs detect vibrations