Waves

Question 1

When will a wave not be refracted

Answer 1

If the mediums have the same refractive index

Or if the wave is traveling along the normal line

Question 2

Which seismic wave is transverse and which is longitudinal

Answer 2

P waves are longitudinal

S waves are transverse

Question 3

What’s a transverse wave

Answer 3

A wave which oscillates perpendicular to the direction of its energy transfer

Question 4

What’s a longitudinal wave

Answer 4

A wave which oscillates parallel to the direction of energy transfer

Question 5

Which waves can be polarised

Answer 5

Transverse

Question 6

What’s the law of reflection

Answer 6

The angle of incidence is always equal to the angle of reflection

Question 7

What is refraction

Answer 7

When a wave hits a boundary of a different refractive index at an angle and it slows down but this causes it to change direction

Question 8

What happens when a wave slows down

Answer 8

It’s wavelength decrease but the frequency stays the same

Question 9

What is superposition

Answer 9

The combined effect of more than 1 wave interfering with each other

Question 10

What’s the principle of superposition

Answer 10

When 2 waves meet the total displacement at a point is equal to the sum of the displacement of both waves

Question 11

What is meant by coherent waves

Answer 11

When waves oscillate at the same frequency with a constant phase difference

Question 12

What is the double slit experiment

Answer 12

A single slit causes diffraction of one wave to produce two coherent waves, they diffract through the double slit to create an interference pattern

Question 13

What is the pattern of fringes due to the double slit experiment

Answer 13

All fringes equally spaces

Question 14

What is the fringe pattern for a single slit experiment

Answer 14

The central fringe is double the width and all the other fringes are equal

Question 15

What is polarised light

Answer 15

Light which only oscillates in one plane

Question 16

What is the path difference for reinforcement

Answer 16

The path difference must be an integer multiple of the wavelength

Question 17

What is the path difference for cancellation

Answer 17

It must be a whole number of wavelengths plus a half extra

Question 18

What can happen to waves when they are reflected

Answer 18

They become partially polarised

Question 19

What is an experiment to demonstrate the wave nature of sound

Answer 19

Diffraction of sound wave through an open door

Question 20

How are stationary waves set up on a string

Answer 20

Two waves, one wave and its reflection, are travelling in opposite directions, they must have the same amplitude frequency and wavelength. They interfere to create a stationary wave

Question 21

What is mew

Answer 21

The mass per unit length

Question 22

What is the name given for an area of no displacement on a stationary wave

Answer 22

Node

Question 23

What does a micrometer measure

Answer 23

The thickness or diameter of something

Question 24

What would you use to measure a gap

Answer 24

A vernier calliper

Question 25

Name safety precautions for a single/double slit experiment

Answer 25

- make sure not to look directly at the lasers - make sure the reflections of the lasers is nowhere near the eyes - place a sign to warn people of use of lasers

Question 26

How does total internal reflection work in fibre optics

Answer 26

A wave is sent down a cable made up of a core and cladding which has a smaller refractive index than the core to allow TIR to occur. A wave is fired down the core at an incident angle greater than the critical angle therefore it is reflected inside the core.

Question 27

What phenomenon happens when white light is sent down a fibre optic

Answer 27

Multipath dispersion

Question 28

What actually happens when white light is passed through an optical fibre

Answer 28

Red light will be quicker due to its higher wavelengths and lower refractive index, therefore it will reach the end first. Due to this time difference it will cause pulse widening

Question 29

What can be done to stop pulse widening

Answer 29

- use monochromatic light - use of shorter repeaters so that the pulse is reinforced - use of monomode fibre to reduce multipath dispersion

Question 30

When does total internal reflection occur

Answer 30

When the refractive index of the first medium is higher than the second and when the angle of incidence is greater than the critical angle

Question 31

What is a wave

Answer 31

An oscillation of particles or fields

Question 32

What's a progressive wave

Answer 32

A wave which carries energy from one place to another without transferring any material

Question 33

What happens to the source of a progressive wave

Answer 33

It loses energy

Question 34

What is proof that progressive waves transfer energy

Answer 34

EM waves cause things to heat up X-rays and gamma rays can cause ionisation Sound waves can make things vibrate Wave power can be used to generate electricity

Question 35

What's an example of transverse waves

Answer 35

Electromagnetic waves Waves on a string Water ripples S waves

Question 36

What are examples of longitudinal waves

Answer 36

Sound Waves on a spring Water waves P waves

Question 37

Which waves can be polarised

Answer 37

Transverse

Question 38

What is an example that EM waves are transverse

Answer 38

They can be polarised

Question 39

What came happen when light is reflected

Answer 39

It becomes partially polarised

Question 40

How do polarised sunglasses work

Answer 40

They have a Polaroid filter at a specific angle to block out unwanted glare from partially polarised light

Question 41

What useful waves are polarised

Answer 41

Tv and radio signals

Question 42

What is a stationary wave

Answer 42

The superposition of two progressive waves with the same frequency and wavelength b traveling in opposite directions

Question 43

Is energy transferred in stationary waves

Answer 43

No

Question 44

What are nodes and anti nodes

Answer 44

A node is where the amplitude is always 0 | An anti nose is a point of maximum displacement

Question 45

When will microwaves cause stationary waves

Answer 45

If they are reflected by a metal plate or wall, they can be shown using a probe

Question 46

What are 3 examples that show stationary waves

Answer 46

- reflected microwaves - lycopodium power in a glass tube - waves on a string

Question 47

What is diffraction

Answer 47

The spreading out of waves as they pass through a gap or around an obstacle

Question 48

Which is diffracted more blue or red

Answer 48

Red

Question 49

What is intensity

Answer 49

The number of photons per second/ power over area

Question 50

Where are most of the photons concentrate on a diffraction pattern

Answer 50

In the central fringe as this has the greatest intensity and therefore has the most photons per second

Question 51

When will a wave be diffracted most

Answer 51

When its wavelength is the same size as the gap

Question 52

What is a good example of diffraction

Answer 52

Sound passing through an open door

Question 53

What is path difference d

Answer 53

The difference in the distance the two waves have travelled

Question 54

When will constructive interference occur

Answer 54

When the path difference is an integer multiple of wavelengths

Question 55

When will destructive interference occur

Answer 55

When the path difference is an interfer and a half wavelengths

Question 56

At what frequency will you get the third harmonic

Answer 56

Three times the resonant frequency