Q. 2

# Can the dispersive power ω=__μ___{v}-μ_{r} be negative? What is the sign of ω if a hollow prism μ-1 is immersed into water?

_{v}-μ

_{r}

Answer :

No, dispersive power can never be negative because for a given medium, μ is a continuous function of wavelength.

In the equation,

ω=__μ _{v}-μ_{r}__

μᵥ is always greater than μᵣ for the transparent prism kept in a medium having a lesser refractive index than it. So μᵥ-μᵣ > 0. Also μ > 1, so μ-1 >0. Hence the dispersive power ⍵ will be positive.

a. If a hollow prism is immersed in water the equation of the dispersive power will become

⍵ = ( - )/ -1

So both the numerator and the denominator will become negative and we will get ⍵ positive.

So in normal situations ⍵ will not be negative.

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HC Verma - Concepts of Physics Part 1Can the dispersive power ω=__μ _{v}-μ_{r}__ be negative? What is the sign of ω if a hollow prism μ-1 is immersed into water?

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