Wave Optics Ques 22

22. The ratio of resolving powers of an optical microscope for two wavelengths $\lambda_1=4000 $ $\AA$ and $\lambda_2=6000 $ $\AA$ is

[2017]

(a) $9: 4$

(b) $3: 2$

(c) $16: 81$

(d) $8: 27$

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Answer:

Correct Answer: 22.(b)

Solution:

  1. (b) Resolving power of a microscope $=\frac{2 \mu \sin \theta}{\lambda}$

i.e., $R \propto \frac{1}{\lambda} \quad$ or, $ \quad \frac{R_1}{R_2}=\frac{\lambda_2}{\lambda_1}$

Given that the two wavelengths,

$\lambda_1=4000 $ $\AA$ and $\lambda_2=6000 $ $\AA$

$\therefore \frac{R_1}{R_2}=\frac{6000 \AA}{4000 \AA}=\frac{3}{2}$