Waves

Question 1

Displacement

Answer 1

Distance from the equilibrium position in a particular direction

Question 2

Amplitude

Answer 2

Maximum displacement from the equilibrium position

Question 3

Wavelength

Answer 3

Minimum distance between two points in a phase on adjacent waves

Question 4

Period of oscillation

Answer 4

Time taken for one complete oscillation

Question 5

Frequency

Answer 5

Number of complete oscillations per second

Question 6

Wave speed

Answer 6

Distance travelled by a wave per unit time

Question 7

Transverse wave

Answer 7

A wave where the direction of oscillation is perpendicular to the direction of energy transfer

Question 8

Longitudinal wave

Answer 8

A wave where the direction of oscillation is parallel to the direction of energy transfer

Question 9

Example of a transverse wave

Answer 9

Light

Question 10

Example of a longitudinal wave

Answer 10

Sound

Question 11

Phase difference

Answer 11

Relates to the oscillation of two points on the (same) wave. How far ‘out of step’ one oscillation is from the other

Question 12

Reflection

Answer 12

A change of direction of a wave at a boundary between two media, remaining in the original medium

Question 13

Refraction

Answer 13

A change of direction of a wave due to a change of speed as it passes from one medium to another

Question 14

Diffraction

Answer 14

When a wave passes through a gap or travels around an obstacle, they spread out

Question 15

Polarisation

Answer 15

Particles oscillate along one direction only

Question 16

Which type of waves can be polarised?

Answer 16

Transverse

Question 17

Partial polarisation

Answer 17

More waves are oscillating in one direction only, but not all of them

Question 18

Intensity of a progressive wave

Answer 18

Radiant power passing through a surface per unit area

Question 19

Equation for intensity

Answer 19

I = P/A , I- intensity, P-radiant power, A- Xarea

Question 20

Units of intensity

Answer 20

W/m^2

Question 21

Intensity equation for a sphere

Answer 21

I=P/4πr^2

Question 22

What is the relationship between intensity and amplitude?

Answer 22

intensity directly proportional to the square of the amplitude

Question 23

List EM spectrum in order of increasing frequency

Answer 23

Radio, Micro, IR, Visible, UV, X, Gamma

Question 24

Speed of light in vacuum

Answer 24

3x10^8 m/s

Question 25

Refractive index equation

Answer 25

n=c/v

Question 26

Snell's law

Answer 26

n1sinθ1=n2sinθ2

Question 27

Total internal reflection

Answer 27

When the light strikes the boundary at a large angle to the normal (angle greater than the critical angle), so it is internally reflected

Question 28

Critical angle

Answer 28

Angle of incidence, which produced an angle of refraction =90

Question 29

What are the conditions for coherent waves (4)

Answer 29

Same freq CONSTANT phase difference Same wavelength Same amplitude

Question 30

Interference

Answer 30

Combined effect of the disturbance cause by the each individual wave at the same place and time

Question 31

Superposition

Answer 31

When two(or more) waves meet, the (resultant) displacement is the (vector) sum of the (individual) displacements add up

Question 32

Progressive wave

Answer 32

A wave which transfers energy as a result of oscillations

Question 33

Stationary wave

Answer 33

A wave which stores energy, where the shape does not move along

Question 34

How does a stationary wave form on a string?

Answer 34

the wave reflected (at the fixed end of the wire) → interferes/superposes with the incident wave → to produce a resultant wave with nodes and antinodes/no energy transfer

Question 35

Path difference

Answer 35

Difference in the distances waves have travelled

Question 36

What is the need of a single slit in Young's Double slit experiment?

Answer 36

To get the waves in phase, so the double slits act as 2 coherent sources

Question 37

What equation is derived from Young's Double slit exp?

Answer 37

λ=(ax)/D D- distance from the screen to the double slit, a distance between the fringes

Question 38

Node

Answer 38

Node occurs where the amplitude/displacement is (always) zero

Question 39

Antinode

Answer 39

Antinode occurs where the amplitude (of the standing wave) takes the only maximum (possible) value

Question 40

What is the distance between 2 adjacent (anti)nodes

Answer 40

half of a wavelength

Question 41

Which particles are in phase AND out of phase AND by how much on a stationary wave

Answer 41

In phase between 2 adjacent nodes | Out of phase outside 2 adjacent nodes by π radians

Question 42

What does fundamental frequency depend on?

Answer 42

String mass, tension, length

Question 43

Fundamental frequency - f0

Answer 43

minimum frequency of a stationary wave of a string

Question 44

What is always true for a standing wave in a closed pipe? (3)

Answer 44

Bottom is always a node Top is always an antinode F=(nv)/4L, L length of the pipe, v speed, n harmonic number

Question 45

What is always true for a standing wave in an open pipe? (2)

Answer 45

1. Each opening is always an antinode | 2. The pipe must be nλ/2