Question

a thin glass lens (refractive index 1.5) has optical power of -5D in air.its optical power in a liquid medium with refractive index 1.6 will be...
1)-25D. 2)25D. 3)-1D. 4) 0.625 D

Answer 1

Answer on Question #52351-Physics-Optics

A thin glass lens (refractive index 1.5) has optical power of -5D in air. Its optical power in a liquid medium with refractive index 1.6 will be...

1)-25D. 2)25D. 3)-1D. 4) 0.625 D

Solution

$$P = \left(\frac {\mu_ {2}}{\mu_ {1}} - 1\right) \left(\frac {1}{R _ {1}} - \frac {1}{R _ {2}}\right).$$ $$- 5 = \left(\frac {1 . 5}{1} - 1\right) \left(\frac {1}{R _ {1}} - \frac {1}{R _ {2}}\right).$$ $$- \frac {5}{0 . 5} = \left(\frac {1}{R _ {1}} - \frac {1}{R _ {2}}\right)\rightarrow \left(\frac {1}{R _ {1}} - \frac {1}{R _ {2}}\right) = - 1 0.$$

Again,

$$P = \left(\frac {1 . 5}{1 . 6} - 1\right) (- 1 0) = \frac {5}{8} D = 0. 6 2 5 D.$$

Answer: 4) 0.625 D.

http://www.AssignmentExpert.com/