18 - The Wave Nature of Light

Learn it

• Heavy base
• Turntable
• Collimator
• Astronomical Telescope

• Cross-threads in focus
• Distant object appears in focus
• Slit is in focus
• Width of the slit
• Level the turntable

*Diffraction or interference

*Red - 7 × 10⁻⁷ m
Orange
Yellow - 6 × 10⁻⁷ m
Green
Blue - 5 × 10⁻⁷ m
Indigo
Violet - 4 × 10⁻⁷ m

The distance between two adjacent slits on a diffraction grating

*
d = [1 ÷ (n × 1000)] metres

*Constructive interference will occur at angle θ if |AB| is a whole number of wavelengths.
i.e. |AB| = nλ where n = 1, 2, 3, etc.

[Need to learn text, but there's more to the proof than that]

*Polarisation

The separating out of the different wavelengths (colours) present in light

*Primary: Red, Green, Blue
R+G: Yellow
R+B: Magenta
G+B: Cyan

formed when two primary colours are mixed in equal intensity

A primary colour and a secondary colour that when mixed give white are called complementary colours

*Prism: Violet the most
Grating: Red the most

*Gamma ray - 0.01 nm
X - Ray - 1 nm
UV - 0.1 μm
Visible Light - 0.4-0.7 μm
Infrared - 0.01 mm
Microwaves - 1cm
TV & Radio: 1m - 1km