Waves

Question 1

Longitudinal vs Transverse waves

Answer 1

Longitudinal: Particles vibrate parallel to direction of energy transfer.
Transverse: Particles vibrate perpendicular to direction of energy transfer.

Question 2

wavelength

Answer 2

difference between 2 successive identical points that have the same oscillation

Question 3

Period

Answer 3

Time per oscillation

Question 4

Frequency

Answer 4

Oscillations per unit time

Question 5

Displacement

Answer 5

Distance a point is from its rest position

Question 6

Amplitude

Answer 6

Max displacement

Question 7

Wave equation

Answer 7

Wavespeed = Freq x Wavelength

Question 8

Intensity Equation

Answer 8

I = Power / Area

Question 9

Intensity & Amplitude Relationsjip

Answer 9

I is directly proportional to A^2

Question 10

Diffraction

Answer 10

Spreading out of waves as it passes around an obstacle or through a gap

Question 11

When is diffraction most pronounced?

Answer 11

When wavelength is similar size to the gap

Question 12

Interference

Answer 12

The addition of 2 or more waves (superposition) creating a resultant wave

Question 13

Order of EM waves (largest to shortest wavelength)

Properties of EM waves

Answer 13

Radio, Micro, Infra-red,Visible Light, Ultraviolet, X-ray, Gamma ray

Speed of 3 x 10^8
Have an electric & Magnetic wave interlocked at right angles to each other

Question 14

What’s a plane polarised wave

What waves can be polarised?

Answer 14

Oscillations of the field & direction of travel are only in 1 field

Transverse

Question 15

Malus’s Law

Amplitude after plane rotated

Answer 15

I = I_max cos^2(-). Max when (-) = 0. 0 when (-) = 90
A = Acos(-)

Question 16

Refraction
How is speed + Direction affected when moving into a material of higher refractive index?
Refractive Index Equation

Answer 16

Wave changing speed & direction due to it passing from one medium to another

Speed decreases, bends towards normal

n = Speed of light in vacuum/Speed of light in material

Question 17

Snell’s law

Answer 17

n1sin(-)1 = n2sin(-)2
OR
nsin(-) = constant

Question 18

Internal Refraction

Critical angle equation: in air, and between 2 materials that arent air

Answer 18

Result of both reflection & refraction when waves travel from high refractive index to low. Below critical angle: refraction & weak reflection. Equal to critical angle: Refracted wave travels along boundary. Above critical: All light is reflected.

SinC = 1/n
SinC = n2/n1

Question 19

Superposition

Answer 19

When 2 or more waves of the same type meet, the resultant wave can be found by adding the displacement.

Question 20

Coherence

Answer 20

2 waves with a constant phase difference.

Question 21

Phase difference & Path difference

Answer 21

Phase: Difference in phases of 2 waves of the same frequency.

Path: Difference in the distance travelled by 2 waves arriving at the same point.

Question 22

Young Double Slit Equation

Conditions necessary

Answer 22

wavelength = fringe seperation x distance between 2 maxima / distance from slit to observed

wavelength = ax/D

Light must be monochromatic (same wavelength)
Must be an accurate method of producing and measuring a small path difference

Question 23

Diffraction Grating Equation

Answer 23

n x wavelength = dsin(-) where n is order of maximum and d is slit seperation

Question 24

Stationary waves

Answer 24

Waves formed by the interference of 2 waves travelling in opposite directions, with the same frequency & similar amplitude.

Question 25

Node & Antinode

Answer 25

Node = 0 displacement
Antinode = max displacement