Waves

Question 1

What are Progressive Waves?

Answer 1

Waves that transfer energy away from a source.

Question 2

What is a Longitudinal Wave?

Answer 2

A wave where the oscillations are parallel to the direction of energy transfer.

Question 3

What is a Transverse Wave?

Answer 3

A wave where the oscillations are perpendicular to the direction of energy transfer.

Question 4

What is the Wavelength of a Wave?

Answer 4

The distance in metres between two successive identical points on a wave, with the same pattern of oscillation.

Question 5

What is the Period of a Wave?

Answer 5

The time taken in seconds for one complete pattern of oscillation to take place.

Question 6

What is the Frequency of a Wave?

Answer 6

The number of oscillations per unit time.

Question 7

What is the Displacement of a Wave?

Answer 7

The distance in meters any part of the wave has moved from its mean/rest position. (can be positive or negative)

Question 8

What is the Amplitude of a Wave?

Answer 8

The Maximum displacement in meters.

Question 9

In a Graphical Representation of a Longitudinal Wave, with pressure on the y-axis. What do peaks and troughs represent?

Answer 9

Peaks- Areas of Compression

Troughs- Areas of Rarefaction

Question 10

How do you find the frequency of a wave on an oscilloscope?

Answer 10

Look at the time setting of the oscilloscope and e.g. 0.002 seconds per division. Then count the number of divisions that make up a period of the wave. Multiply this by the time base and inverse it to find the frequency of the wave.

Question 11

How does the intensity of a wave relate to its amplitude?

Answer 11

Intensity is directly proportional to Amplitude Squared.

Question 12

What is Reflection?

Answer 12

When waves rebound from a barrier, changing direction but remaining in the same medium

Question 13

What is Refraction?

Answer 13

When waves change direction when they move from one medium to another, due to the difference in wave speed between each medium.

Question 14

What is Diffraction?

Answer 14

When a wave spreads out after passing an obstacle or going through a gap.

Question 15

Which EM waves are non-ionising?

Answer 15

Radio waves to visible light

Question 16

What are the three types of UV and what do they do?

Answer 16

UV-A: Causes tanning
UV-B: Causes Cancers and Sunburn
UV-C: Filtered by atmosphere

Question 17

What is a Plane-Polarised Wave?

Answer 17

A transverse wave that oscillates in only one plane

Question 18

What is a polarising filter?

Answer 18

A filter that produces plane polarised light by selective absorption of one component of the incident oscillations. The filter transmits only the component of light polarised perpendicular to that direction.

Question 19

What does Malus’ law state?

Answer 19

When a perfect polariser is put in a beam of polarised light, the intensity of the light that passes through is given by: I = I(max) cos2θ

Question 20

What is Snell’s law?

Answer 20

n1sinθ1 = n2sinθ2

Question 21

What is the critical angle with respect to total internal reflection?

Answer 21

The angle after which no refraction will take place and all incident waves will be reflected.

Question 22

What does the principle of superposition state?

Answer 22

When two or more waves of the same type meet, the resultant wave can be found by adding the displacements of the individual waves.

Question 23

What is interference?

Answer 23

The addition of two or more waves (superposition) that results in a new wave pattern. This can be constructive when waves travel at the same point in phase or destructive when two waves are in anti-phase.

Question 24

What is coherence?

Answer 24

Two waves having a constant phase relationship.

Question 25

What is path difference?

Answer 25

The difference in meters between the distances travelled by two waves arriving at the same point. It can be written in terms of wavelengths e.g. 1/4 λ

Question 26

What is phase difference?

Answer 26

The difference in the phases of of two waves of the same frequency. Written as an angle e.g. 180° or π rad

Question 27

What is Young’s double slit experiment?

Answer 27

An experiment demonstrating the wave nature of light via superposition and interference.

Question 28

How is Young’s double slit experiment conducted?

Answer 28

A monochromatic red light source is placed behind a single slit. The wave then spreads out via diffraction, until it reaches another two parallel slits. Since the light is now coherent, waves from both slits are in phase so the waves will diffract in interfere with each other. This causes alternate bright and dark vertical bands to be shown on the screen

Question 29

What is a diffraction grating and what is it used for?

Answer 29

It is a piece of optical equipment that enables light to be diffracted at different angles based off of the wavelength of the light and the separation of the grooves.

Question 30

what are stationary/standing waves?

Answer 30

Waves that are in a fixed position with their energy in a fixed position.

Question 31

How are stationary waves formed?

Answer 31

By, the interference of two waves travelling in opposite directions, with the same frequency and amplitude when they cross each other.

Question 32

What are nodes on a stationary wave?

Answer 32

Points at which there is no displacement of the particles at any time.

Question 33

What are antinodes on a stationary wave?

Answer 33

Points at which the displacement of the particles vary at the maximum amount.