8.2, 8.3 Diffraction, Inteference

Principle of superposition: w__ _ w__ m__ a_ _ p__, r__ d__ e__ s__ o_ d__ o_ i__ w__

when 2 waves meet at a point, resultant displacement equals sum of displacements of individual waves

Diffraction: s__ of w__ when passing thru a g__ OR past the e__ of an obj
> most prominent when g__ width ~=~ w__

spreading, wave, gap, edge, gap, wavelength

incr wavelength = __ (more/less) spreading

more

incr gap width = __ (more/less) spreading

less

Interference: s__ o_ _ w__ f__ c__ s__

superposition of 2 waves from coherent sources

Coherent source: h__ s__ _ & _/c__ p__ d__

has same f, 0/constant phase diff

Path diff: e__ d__ t__ b_ _ w__ c__ w/ a__ (in terms of wavelengths)

extra distance travelled by 1 wave compared w/ another

constructive or destructive

constructive

constructive or destructive

destructive

Constructive waves
> (in phase/anti-phase)
> (maxima/minima)
> path diff = __ (__ no.)

in phase, maxima, nlambda, whole

Destructive waves
> (in phase/anti-phase)
> (maxima/minima)
> path diff = __

antiphase, minima, (n+1/2) lambda

w/ sound:
> louder = __ waves
> no sound = __ waves

constructive, destructive

Microwaves:
> detector picks up max amplitude = __ waves
> detector picks up m__/_ amplitude = __ waves

constructive, min/0, destructive

Light:
> constructive: __
> destructive: __

bright, dark

2 source interference fringes

maxima

2 source interference fringes

minima

2 source interference fringes

path diff

When observing 2-source interference fringes:
> source must be c__ & m__ (single w__) e.g. l__

coherent, monochromatic, wavelength, laser

a

D

DISTANCE BETWEEN ADJ. __ FRINGES

x, bright

For λ = ax/D:
incr x when:
> __ (incr/decr) λ
> __ (incr/decr) D
> __ (incr/decr) a

incr, incr, decr