WAVES

Question 1

360’ in radians

Answer 1

2pi rad

Question 2

1 wavelength in radians

Answer 2

2pi radians

Question 3

Transverse wave examples

Answer 3

EM waves, light waves, waves on string

Question 4

Longitudinal Wave Examples

Answer 4

Sound waves, seismic-P waves

Question 5

What does a polarising filter do?

Answer 5

Let wave pass in one direction/ plane.
Transverse only

Question 6

Aerial use

Answer 6

transmission and reception

Question 7

Characteristics of single slit diffraction (monochromatic)

Answer 7

central maximum with many dimmer smaller maxima

Question 8

Characteristics of double slit diffraction (monochromatic)

Answer 8

central maximum same size as maxima gets dimmer

Question 9

Characteristics of single slit diffraction (white light)

Answer 9

Large central maximum, spectrum maxima, violet closest to maximum range to red furthest away

Question 10

What does a single slit ensure

Answer 10

Ensures light of one specific wavelength, (therefore same frequency) can pass into the double slits.

Question 11

How are bright fringes formed

Answer 11

Caused by constructive interference, occurs when superposition occurs. Phase difference has to be a multiple of 2pi rad or 0pi rad. (In phase)

Question 12

Spectrometer

Answer 12

Shows the intensity of the light emitted (diffraction pattern)

Question 13

d = a lines per mm
convert to m

Answer 13

1/d10^3

Question 14

find total amount of orders (diffraction grating)

Answer 14

n = dsin(90)/wavelength

Question 15

Pulse Absorption

Answer 15

Signal absorbed by material. Loses energy through reducing amplitude.

Question 16

Countering signal degradation

Answer 16

Repeaters (signal booster)

Question 17

Modal dispersion

Answer 17

Signals take different paths in a fibre. Signal will be received at different times. Results in pulse broadening. Signal may overlap. Minimise fibre used to counter this.

Question 18

Material dispersion

Answer 18

Different wavelengths of light arriving at different times. Refractive index of fibre changes with frequency. Pulse broadens. Signals overlap. Monochromatic light used to counter this.

Question 19

Appearance of visible line emission spectrum using diffraction

Answer 19

coloured lines, dark background

Question 20

Particle behaviour of electron beam

Answer 20

randomly scattered, small spots of light

Question 21

Wave behaviour of electron beam

Answer 21

Through diffraction and interference. Bright rings occur when constructive interference is taking place

Question 22

mew in terms of density and area

Answer 22

density x area

Question 23

if frequency is proportional to square root of tension, explain how frequency produced from actual experiment is different from predictions.

Answer 23

L and mew (mass per unit length) has to be constant. If tension is too great, string will stretch, therefore lower mass per unit length. Therefore frequency will be greater.

Question 24

blue light and red light optics

Answer 24

blue undergoes TIR, Red will refract. Critical angle for red is more and less for blue.

Question 25

blue light and red light refractive index, which is greater?

Answer 25

blue has a greater refractive index and refracts more than red (smallest refractive index)

Question 26

TIR

Answer 26

when angle of incidence is greater than critical angle

Question 27

cladding refractive index

Answer 27

n(cladding)

Question 28

lines per mm to grating space (m)

Answer 28

x1000, reciprocal

Question 29

relationship between n and wavelength

Answer 29

n inversely proportional to wavelength dsin(0)=n(wavelength)

Question 30

Why is it important to align the aerial of a TV to receive strongest signal? (EM waves)

Answer 30

Similar in nature to transverse waves, which can be polarised. Aerial must be aligned in the same plane of wave.

Question 31

Rarefactions and Compressions

Answer 31

R - regions of decreased pressure C - regions of increased pressure

Question 32

Path difference

Answer 32

n x wavelength (n is an integer) pd is a multiple of the wavelength

Question 33

path difference + phase difference of destructive interference

Answer 33

Path d - (n + 1/2) wavelength Phase d - 180 degree, anti phase

Question 34

State the path difference between light from adjacent slits when this light produces a first-order maximum on the screen.

Answer 34

one wavelength

Question 35

Explain how light from the diffraction grating forms a maximum on the screen (3)

Answer 35

waves overlap, their path difference is a whole number of wavelengths, they undergo superposition.

Question 36

What are the three types of damping?

Answer 36

Heavy Damping Critical Damping Light Damping

Question 37

What is Damping?

Answer 37

The loss of energy of oscillations to the environment

Question 38

What is Heavy Damping

Answer 38

Overdamping, when the amplitude reduces slower than with critical damping but also without oscillations

Question 39

Light Damping

Answer 39

Under damping, when amplitude gradually decreases by a small amount each oscillation

Question 40

What is Critical damping

Answer 40

Reduces amplitude to zero in the quickest and shortest possible time without oscillation

Question 41

Why do systems use narrow optical fibres

Answer 41

different paths of light through the fibre take different times to travel this causes the signal to spread if fibre is wide

Question 42

Why do signalling systems use monochromatic light

Answer 42

Different wavelengths travel at different speeds causing signal to spread