Transparent Glass Prism

LIGHT

A

δm

Incident ray

Initial direction

Emerging ray

A is the angle of prism

N N

N is normal on the surface of prism

δm is the deviation of emerging ray from initial direction

Prism

Prism and refraction

Red 6600 Å Orange 6100 Å Yellow 5800 Å Green 5500 Å Blue 4700 Å Indigo 4400 Å Violet 4100 Å

wavelength λ of the center of color band in angstroms

prism

Dispersion of white light of sun by prism

white light

A

Spectrum

If a shaft of light entering a prism is sufficiently small such that the coloured edges meet, a spectrum results

white light Spectrum

An experiment to observe spectrum

δR δVΘ

A

White light

δm ⇒ mean deviation or deviation for yellow

Angle of dispersion θ

θ = δV - δR

Dispersive power ω

δm

θω =

δm

ω =δV - δR

Deviation by prism

δR ⇒ deviation for red

δV ⇒ deviation for violet

δm