Question

Pick out the formula for dispersive power from the following.

(a) Dispersive power = \(\frac {mean \, deviation}{angular \, dispersion }\)

(b) Dispersive power = mean deviation * angular dispersion

(c) Dispersive power = mean deviation + angular deviation

(d) Dispersive power = \(\frac {angular \, dispersion}{mean \, deviation}\)

The question was asked in class test.

Enquiry is from Ray Optics in chapter Ray Optics and Optical Instruments of Physics – Class 12

Answer 1

The correct answer is (d) Dispersive power = \(\frac {angular \, dispersion}{mean \, deviation}\)

The explanation: The formula for dispersive power is given as:

Dispersive power (ω)=\(\frac {Angular \, dispersion (\delta_V-\delta_R)}{Mean \, deviation (\delta)}\)

ω=\(\frac {\mu_V-\mu_R}{\mu-1}\)

Where μ=\(\frac {\mu_V+\mu_R}{2}\) = mean refractive index