C.3 Wave Phenomena

Question 1

What happens to a wave when it travels from one medium into another?

Answer 1

• some of the waves energy is reflected
• some of the waves energy will enter the medium and change speed, this change in speed is called refraction
• some of the energy will be absorbed as it travels through the medium (transmission)

Question 2

transmission

Answer 2

The passage of a wave through the medium

Question 3

refraction

Answer 3

the change in speed of a wave as it enters a new medium

Question 4

incident ray

Answer 4

ray travelling towards new medium

Question 5

reflected ray

Answer 5

ray that is reflected off the boundary

Question 5

angle of incidence

Answer 5

angle between incident ray and the normal

Question 6

angle of relection

Answer 6

angle between reflected ray and normal

Question 7

normal

Answer 7

perpendicular/ 90° to boundary

Question 8

refracted ray

Answer 8

the ray that passes through into the new medium (will have changed speed)

Question 9

angle of refraction angle between normal and refracted ray

Answer 9

angle between normal and refracted ray

Question 10

What happens if the angle of incidence hits at an angle greater than 0°/ along normal?

Answer 10

It will change direction as well as speed

Question 11

When slowing down in the new medium will the refracted ray bend towards or away from the normal?

Answer 11

Towards the normal

Question 12

When speeding up in the new medium will the refracted ray bend towards or away from the normal?

Answer 12

away from the normal

Question 13

refractive index (n)

Answer 13

A measure of how fast a wave travels in the medium. The larger n is the slower the wave travels (and vice versa)

Question 14

Snells law only applies to ___ if the first medium is ___

Answer 14

Light (waves), air

Question 15

For a wave to travel its highest speed in a medium the refractive index for that medium must be ….

Answer 15

n=1.0

Question 16

The value for refractive index (n) is always….

Answer 16

Greater than or equal to 1.0

Question 16

Snells Law formula

Answer 16

n=sin i/sin r, where i is the angle of incidence and r is the angle of refraction

Question 17

refractive index (n) units

Answer 17

no units because it is a ratio

Question 18

What can Snells Law be used to find

Answer 18

the refractive index (n) of a medium for light

Question 19

When does total internal reflection of light occur?

Answer 19

When light is travelling from a more to less optically dense medium (it is speeding up/n is getting smaller) and when the angle of incidence is greater than the critical angle

Question 20

What happens when the angle of incidence= the critical angle

Answer 20

refraction at 90°, (refracted ray travels along boundary)

Question 21

Wavefront

Answer 21

A line connecting points on a wave with the same phase/displacement (line at 90° to the direction of motion of the wave)

Question 22

Ray

Answer 22

Line drawn to represent the direction a wave is travelling when viewed from above showing the direction of energy transfer

Question 23

Rays are drawn at __° to wavefronts

Answer 23

90

Question 24

distance between wavefronts=….

Answer 24

wavelength

Question 25

Diffraction

Answer 25

The spreading out of waves as they move past an obstacle or through a gap

Question 26

Diffraction when moving past an obstacle

Answer 26

the edge of the wave that hits the obstacle tends to spread out. Longer wavelengths diffract more.

Question 27

Diffraction when moving through a gap

Answer 27

The width of the gap relative to the wavelength will effect how the wave spreads out. If gap width= λ, circular wavefronts are produced (looks life wifi symbol). If not they look like lines the width of the gap with slightly curved sections on the ends.

Question 28

What happens to the amplitude after diffraction?

Answer 28

The amplitude decreases as the energy becomes spread out over a longer wavefront.

Question 29

Alternative name for interference

Answer 29

Superposition of waves

Question 30

Constructive Interference

Answer 30

When waves meet in phase. Forms a resultant wave with an amplitude equal to the sum of the amplitudes if the individual waves.

Question 31

Destructive interference

Answer 31

When waves meet 180° out of phase (upside down). They will cancel each other out to give a wave of zero amplitude (assuming both waves had the same amplitude)

Question 32

When is the Principle of Superposition used

Answer 32

Between the two extremes (in phase and 180° out of phase), to determine the amplitude of the resultant wave

Question 33

Principle of Superposition

Answer 33

“If two or more waves meet, the resultant displacement at any point is found by adding the displacements produced by each individual wave”

Question 34

Is the antinodal line of a light wave bright or dark?

Answer 34

Bright

Question 35

Is the nodal line of a light wave bright or dark?

Answer 35

Dark

Question 36

Is the nodal line of a sound wave loud or quiet?

Answer 36

Quiet

Question 37

Is the antinodal line of a sound wave loud or quiet?

Answer 37

Loud

Question 38

Requirements for an interference pattern to be produced

Answer 38

Two waves must be the same type and be coherent (have a constant phase relationship)

Question 39

What did Young’s Double slit interference experiment prove

Answer 39

That light is a wave not a particle as it can diffract and interfere