Question

While calculating the focal length of a lens formula; what is different when the lens is immersed in or surrounded by some other medium than that of air?

• A. ${\mu }_1$
• B. ${\mu }_2$
• C. $R_1\&R_2$
• D. $Noneofthese$

Answer 1

The correct option is A ${\mu }_1$

In Lens maker's formula;,
$\frac{1}{f}=(\frac{{\mu }_2}{{\mu }_1}-1)(\frac{1}{R_1}-\frac{1}{R_2})$
${\mu }_1$ is the refractive index of the surrounding, so if the surrounding changes, ${\mu }_1$ changes; everything else remains the same.