12 Superposition

Question 1

The principle of superposition

Answer 1

When waves meet, the actual displacement is the vector sum of separate displacements of the individual waves and each waves proceeds as though no other waves exist

Question 2

stationary wave

Answer 2

A stationary wave is a wave with no transfer of energy

A stationary wave is formed from the superposition of two progressive wave trains of
equal amplitude and frequency
travelling with the same speed in opposite directions
over the same space

Question 3

formula for double slit interference

Answer 3

𝛌=ax/D

Question 4

formula for single slit diffraction

Answer 4

sin(angle from first minimum and central maximum to centre of slit) =𝛌/b

Question 5

Rayleigh’s criterion

Answer 5

Rayleigh’s criterion says the images of two point sources can just barely be distinguished from each other if the central maximum of one diffraction pattern falls onto the first minimum of the other one

Question 6

Rayleigh’s criterion formula

Answer 6

angles between the two sources from the centre of the slit =𝛌/b

Question 7

Formula for dfffraction at a grating

Answer 7

d sin θn=n𝛌

θn = angle between nth order maximum and central maximum from the centre of the slit

Question 8

Diffraction

Answer 8

Diffraction is the spreading of waves when they pass through an opening or around an obstacle

Question 9

Conditions for observable interference

Answer 9

Sources must be coherent (constant phase difference)

The waves cannot be polarised in mutually perpendicular planes

The amplitude of both waves must be similar

The two waves from the sources must superpose