Question

Find the radius of first zone is a zone plate of focal length 25 cm for light of wavelength 5000 A.

Answer 1

Explanation:

500 anstrom is the radious of wavelength of focal length

Answer 2

The radius of first zone is a zone plate of focal length 25cm for the light of wavelength 5000Â is 0.03cm.

Given,

$f_{1} = 25cm.$

λ = 5000Â. = 5×$10^{-5}$cm.

Find,

Radius of first zone = ?

Formula used,

$f = \frac{r^{2} }{n(lambda)}$

$r = \sqrt{f(lambda)} \\\\r = \sqrt{25(5(10^{-5})) }\\ \\r = 0.03cm.$

Therefore, the radius of first zone is a zone plate of focal length 25cm for the light of wavelength 5000Â is 0.03cm.