Superposition

Question 1

What is the principle of superposition?

Answer 1

When two waves meet, the resultant displacement is the vector sum of displacements due to each individual wave.

Question 2

What is coherence?

Answer 2

Sources are said to be coherent if they have constant phase difference. It also implies that they have the same frequency.

Question 3

What are stationary waves?

Answer 3

Stationary waves result from the superposition of two waves of equal amplitude and frequency travelling with same speed but in opposite directions.

Question 4

What is diffraction?

Answer 4

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

Question 5

Formula for double slit experiment

Answer 5

x = λD/a
x is fringe separation
λ is the wavelength
D is the distance between screen and double slit
a is the distance seperating the two slits.

Question 6

Formula for single slit diffraction

Answer 6

sinθ = λ/b
θ is the angle that the first minima makes with the central maxima
λ is wavelength of the light
b is width of the slit

Question 7

What is Rayleigh’s criterion?

Answer 7

Rayleigh’s criterion states that two sources are just resolved if the central maximum of one diffraction pattern falls on the first minimum of the diffraction pattern of the other.
θ = λ/b

Question 8

Formula for diffraction grating

Answer 8

dsinθ = nλ
d is separation between slits
n is order of maxima
θ is the angle that the nth order of maxima makes with central maxima