Question
From the given data set, determine angular dispersion by the prism and dispersive power of its material for extreme colours. $nR = 1.62 nv = 1.66, δR = 3.1^\circ $

Answer

Given: $n_R = 1.62, n_V = 1.66, δ_R = 3.1^\circ $
To find:
i. Angular dispersion $(δ_{vr})$
ii. Dispersive power $(ω_{VR})$
Formula:
i. $δ = A (n – 1)$
ii.$δ_{VR} = δ_V – δ_R$
(iii) $\omega=\frac{\delta_{ V }-\delta_{ R }}{\left(\frac{\delta_{ V }+\delta_{ R }}{2}\right)}$
Calculation: From formula (i),
$ \delta_{ R }= A \left( n _{ R }-1\right)$
$\therefore A =\frac{\delta_R}{\left(n_R-1\right)}=\frac{3.1}{(1.62-1)}=\frac{3.1}{0.62}$
$=5$
$\delta V = A \left( n _{ V }-1\right)=5 \times(1.66-1)=3.3 C $
From formula (ii),
$\delta_{ VR }=3.3-3.1=0.2^{\circ}$
From formula (iii),
$ \omega_{V R}=\frac{3.3-3.1}{\left(\frac{3.3+3.1}{2}\right)}=\frac{0.2}{6.4} \times 2=\frac{0.2}{3.2}=\frac{1}{16}$
$=0.0625 $

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