4. The nature of waves

Question 1

What are transverse waves?

Answer 1

Particle oscillations perpendicular to propagation of the wave

Question 2

Examples of transverse wave?

Answer 2

• Water waves
• S-Waves (seismic)
• Vibrations on a guitar string
• Em-waves

Question 3

What are longitudinal waves?

Answer 3

Particle oscillations parallel with propagation of the wave

Question 4

Examples of longitudinal waves?

Answer 4

• Sound waves
• P-waves (seismic)
• Ultra-sound

Question 5

What are progressive waves?

Answer 5

Transfers energy from one place to another with no net movement of particles/material

Can be either transverse/longitudinal

Question 6

What’s the amplitude of a wave?

Answer 6

Maximum displacement of a wave when measured from the equilibrium position

unit: metres (m)

Question 7

What’s the wavelength of a wave?

Answer 7

Distance between adjacent peaks of a wave
[Distance between adjacent points on a wave that are in-phase]

unit: metres (m)

Question 8

What’s frequency of a wave?

Answer 8

Number of wavelengths passing a point per unit time

unit: Hertz (Hz)

Question 9

What’s the period of wave?

Answer 9

Time taken for a wave to make one complete oscillation

unit: seconds (s)

Question 10

How to find the frequency of wave using period?

Answer 10

It’s just f = 1/T

(in booklet, if u know u know)

Question 11

What’s wave displacement?

Answer 11

Distance and direction of a vibrating particle in a wave measured from its undisturbed position

unit: metres (m)

Question 12

In a wave displacement graph, displacement along length of wave = ??? graph?

Answer 12

Displacement distance graph

Question 13

In a wave displacement graph, displacement with time for a point on the wave = ?? graph?

Answer 13

Displacement time graph

Question 14

If it’s in phase, what it mean?

Answer 14

Doing same thing at the same time

Question 15

If it’s in antiphase, what it mean?

Answer 15

Doing opposite things at same time

Question 16

Explain all about phase angle

Answer 16

• So u already know where a wave starts within a graph
• In terms of angles, within a circle:
• It starts pointing right with 0°
• It goes anti-clockwise and each quarter is 90°
• Therefore when u reach back to the beginning it’d be 360°

Btw, 360° = 2π
but 180° = π

Question 17

How to find wave velocity?
include light waves too
(only light wave in data booklet)

Answer 17

V = f x λ
Velocity = Frequency x Wavelength

C = f x λ

Question 18

Define polarisation

Answer 18

The process of turning an unpolarised wave
- (vibrations in many planes)
into a plane polarised wave
- vibrations only in one plane

req. a polariser

Question 19

5 uses of polarisation?

(at least know some)

Answer 19

1. Sunglasses
2. 3D cinema
3. Strain analysis
4. TV and radio transmission
5. Headphones

Question 20

Explain the 5 uses of polarisation?

Answer 20

Later

Well…. could I?