CHAPTER 12: SUPERPOSITION

Question 1

stationary wave

Answer 1

a stationary wave is formed from the superposition of two progressive wavetrains of equal amplitude and frequency (therefore wavelength) travelling with the same speed in opposite directions over the same space. there is no propagation of energy along the wave, and thus a stationary wave is characterised by nodes and antinodes occuring at fixed positions

Question 2

coherent sources

Answer 2

constant phase difference, same frequency

Question 3

interference

Answer 3

the result of superposition of wavetrains from a finite number of coherent sources

Question 4

doube slit formula

Answer 4

lambda = ax/D
a = distance between double slits
x = separation of fringes

Question 5

single slit formula

Answer 5

sin theta = lambda/b
theta = angle from first minimum and central maximum
b = width of slit

Question 6

rayleigh’s criterion

Answer 6

the images of two point sources can just barely be distinguished from each other (resolved) if the central maximum of one diffraction pattern falls on the first minimum of the other one

formula : theta = lambda/b

Question 7

diffraction grating formula

Answer 7

d sin theta = n lambda