Question

The Cauchy's formula is

• A. $\mu =A+B{\lambda }^2+C{\lambda }^4$
• B. $h=A+B{\lambda }^2+C{\lambda }^2$
• C. $\mu =A-B{\lambda }^2+C{\lambda }^4$
• D. $\mu =A+B{\lambda }^{-2}+C{\lambda }^{-4}$

Answer 1

Answer: (D)

From Cauchy's dispersion formula the refractive index $(\mu )$ and wavelength $(\lambda )$ are related as follows:
$\mu =A+\frac{B}{{\lambda }^2}+\frac{C}{{\lambda }^4}$
$\Rightarrow \mu =A+B{\lambda }^{-2}+C{\lambda }^{-4}$