(3.1) - Progressive and Stationary Waves

Question 1

Amplitude

Answer 1

The maximum displacement of a wave from its equilibrium

Question 2

Frequency

Answer 2

The number of complete wave cycles that pass a given point in one second

Question 3

Wavelength

Answer 3

The distance between two consecutive points that are in phase on a wave

Question 4

Speed

Answer 4

The rate at which a wave travels through a medium

Question 5

Phase

Answer 5

The position of a point within one complete cycle of a wave

Question 6

Phase difference

Answer 6

The difference in phase between two points on a wave or between two waves

Question 7

Definition, properties, and examples

Longitudinal Waves

Answer 7

1. Oscillates parallel to direction of wave travel
2. Compressions and rarefractions
3. Sound waves, seismic P

Question 8

Definition, properties, and examples

Transverse Waves

Answer 8

1. Oscillates perpendicular to the direction of wave travel
2. Oscillates in crests and troughs
3. Waves on a string, seismic S

Question 9

Polarisation

Answer 9

Particle oscillations occur in only one of the directions perpendicular to the direction of wave propagation

Question 10

Why can’t longitudinal waves be polarised

Answer 10

They only oscillate parallel to direction of travel

Question 11

Uses of polarisation

Answer 11

• Photography (reduces glare an reflections from water or glass)
• Sunglasses (reduce glare)

Question 12

Examples and how they work

Polarisation in Alignment of Aerials for Transmission and Reception

Answer 12

• Radio and TV signals (Signals are polarised, so the receiving aerial must be aligned with the same polarisation as the transmitted signal.

Question 13

What is a stationary wave?

Answer 13

Two waves with same frequency and amplitude travel in opposite directions and interfere with each other

Question 14

What is a node?

Answer 14

Region on stationary wave with no vibrations

Question 15

What is an antinode?

Answer 15

Region on stationary wave where vibrations are at maximum amplitude

Question 16

Superposition

Answer 16

Two or more waves with the same frequency arrive at a point, the resultant displacement is the sum of the displacements of each wave

Question 17

‘In phase’

Answer 17

Two waves that both:
* have the same frequency
* are at the same point in their cycles at the same time

Question 18

‘Anti-phase’

Answer 18

Two waves that both:
* Have the same frequency
* Have a phase difference of 180 degrees

Question 19

‘Out of phase’

Answer 19

Two waves that:
* Can have the same of different frequencies
* Can have any phases difference, except 0, and any multiple of 180 degrees