Question

The radii of the two curves of the bi-convex lens are 60cm, 60cm. Find the focal length of the lens where the lens

refractive index n=1.5.​

Answer 1

PLS MARK BRAINLIEST  IF U HAVE HUMANITY LEFT

I just want to level up.

Anyway, here's ur answer:

Let R = 60cm      [Radius of one of the curves]

Let r  = -60cm     [Radius of the other curve & it is negative because it is opp. to the first curve]

u = 1.5 cm            [Refarctive Index]

f = ?                     [Focal Length]

From lens maker's formula,

$\frac{1}{f} =(u-1)(\frac{1}{R} + \frac{1}{r} )$

$\frac{1}{f} = (1.5-1)(\frac{1}{60} + \frac{1}{-60})$

$\frac{1}{f} = (1.5-1)(\frac{1}{60} - \frac{1}{60})$

$\frac{1}{f} = (0.5)(\frac{2}{60})$

$\frac{1}{f} = (0.5)(\frac{1}{30})$

$\frac{1}{f} = (\frac{0.5}{30})\\\\\frac{1}{f} = (\frac{0.5*10}{30*10})\\\\\frac{1}{f} = (\frac{5}{300} )$

$f = \frac{300}{5} \\\\Therefore,\\f = 60cm$

HOPE IT HELPED U :- ]