Waves

Question 1

What does the angle of incidence equal if it reflects of the boundary and remains in the same medium

Answer 1

Angle of refraction

Question 2

Conditions of superposition

Answer 2

Same wave type
Constant phase difference
Opposite direction
Same frequency / speed
Same amplitude

Question 3

Width of central Maxima compared to subsequent maxima

Answer 3

Double

Question 4

Single slit diffraction pattern

Answer 4

Larger central Maxima, intensity decreases rapidly either side

Question 5

Is red or blue light more likely to experience TIR and why?

Answer 5

Blue light, as it has a larger refractive index and therefore lower critical angle.

Question 6

How to find the wavelength of a longitudinal wave?

Answer 6

The distance between the centre of 2 corresponding compressions

Question 7

Impact of increased wavelength on central maxima

Answer 7

Wider, but less intense

Question 8

Coherent sources: 2 conditions

Answer 8

Same frequency/wavelength
Fixed phase difference

Question 9

Difference between microwaves and soundwaves

Answer 9

Longitudinal and transverse
Microwaves can travel through a vacuum (sound needs matter)
Microwaves can be polarised

Question 10

What’s the fundamental frequency

Answer 10

The 1st harmonic / the lowest frequency of a periodic waveform

Question 11

When ∅i = ∅r

Answer 11

Reflection

Question 12

Diffraction def

Answer 12

The spreading of waves when they pass through a gap

Question 13

Antinode def

Answer 13

A position of maximum displacement in a stationary wave

Question 14

Optical fibre def

Answer 14

A thin glass fibre through which signals are passed through and usually have a cladding surrounding them

Question 15

Phase difference def

Answer 15

The difference in phase between two points on a wave.

Question 16

Polarisation def

Answer 16

The restriction of a wave so that it can only oscillate in a single plane.

Question 17

Longitudinal wave def

Answer 17

A wave with oscillations that are parallel to the direction of energy propagation.

Transverse wave (secondary wave)
Longitudinal (primary wave)

Question 18

Why use light rather than electrons in an optical fibre?

Answer 18

Less energy lost that would be caused due to heating from the resistance of the wire it would travel through compared to signal degradation.
Also slower (slightly)

Question 19

Why is infrared used for optical fibres more often than light?

Answer 19

Easier to restrict than monochromatic light therefore easier to stop material dispersion.

Question 20

Functions of core and cladding in optical fibre

Answer 20

Core: where EM waves travel (transmission medium)

Cladding: provides lower refractive index at the cores boundary to cause TIR and offers protection from scratching which could lead to light leaving the core.

Question 21

Sound waves can perform TIR and they would travel in a low medium and have a high refractive index medium as there cladding (opposite to transverse waves, since sound waves travel faster through a medium)

Question 22

Fringe spacing def

Answer 22

The distance between two adjacent bright/dark fringes