First slide

Dispersion

Question

The dispersion for a medium of wavelength $λ$ is D, then the dispersion for the wavelength 2 $λ$ will be

Moderate

A

$\frac{D}{8}$
B

$\frac{D}{4}$
C

$\frac{D}{2}$
D

D

Solution

$∵ μ = a + \frac{b}{λ^{2}} (Cauchy's equation) and dispersion D = - \frac{dμ}{dλ} \Rightarrow D = - (- 2 λ^{- 3}) b = \frac{2 b}{λ^{3}} \Rightarrow D \propto \frac{1}{λ^{3}} \Rightarrow \frac{D^{'}}{D} = {(\frac{λ}{λ^{'}})}^{3} = {(\frac{λ}{2 λ})}^{3} = \frac{1}{8} \Rightarrow D^{'} = \frac{D}{8}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App