Waves

1
Waves
2
frequency
f
3
frequency 1 period

• f 1
• T

4
Interference

• Constructive

Waves in phase
5
Interference

• Destructive

Waves out of phase
6
Coherent sources

• Waves in phase

Same frequency
7
monochromatic

• Single frequency

8
Path difference

• Maximum occurs when

path difference n l
9
Path difference

• Minimum occurs when

path difference (n1/2) l
10
Diffraction grating

• n l

d sin q
11
To increase q

• Increase wavelength

decrease slit separation d
12
Common Wavelengths

• Red light

700 nm
Green light
540 nm
Blue light
490 nm
13
Spectra - prism
red

• white

violet
14
Spectra - grating
red
violet
red

• white

white
red
violet
red
15
Refractive index
air
glass
qglass
qair
16
Refractive index
sin qair
n
sin qglass
17
Refractive index
lair
n
lglass
18
Refractive index
vair
n
vglass
19
Refractive index
frequency
remains
constant
20
Critical Angle
1
n
sin qc