Interference and DIIHfraction

Thomas Young

did the most convincing experiment that light is a wave

Interference Pattern

pattern of alternating bright & dark bands formed

Interference

simply the combination of waves

Principle of Superposition

When two waves meet, the forces of their particles are added together

greater amplitude

what is the amplitude if waves meet in phase

lesser amplitude

what is the amplitude if waves meet out of phase

bright fringe

Fringe of in phase

dark fringe

fringe of out phase

constructive interference

crest meets crest

destructive interference

crest meets trough

2 smaller waves

what is created because of diffraction?

central bright fringe

what is created because of superposition

central bright fringe

brightest fringe

1/2

lambda of dark fringe

Interference fringes

formed when 2 diffracted light beams from the double slit overlap

bright fringe

formed when the light from one slit reinforces the light from the other slit

bright fringe

path differences equal to a whole number of wavelengths

dark fringe

formed due to a cancellation where the light from the slit is 180° out of phase

y=mλL/d

Equation of Bright Fringe

(m+1/2)λL/d

Equation of Dark Fringe

P.D=mλ or P.D=dsinθ

Equation for the path difference

P.D=mλ

constructive interference equation

P.D=dsinθ

destruction interference equatiom

diffraction

another way to look at path difference

path difference

difference in distance