Question

A double convex lens has radii of curvature of 40 cm and 10 cm. The refractive index of the
material of the lens is 1.545. Calculate the focal length of the lens?
a) 20.2 cm
b) 12.8 cm
c) 24.2 cm
d)15.55cm​

Answer 1

focal length of double convex lens is 14.67 cm. and nearest value of 15.55 cm so we can select option (D) 15.55

A double convex lens has radii of curvature of 40 cm and 10 cm. the refractive index of the

material of the lens is 1.545.

here, R1 = 40cm, R2 = -10cm and μ = 1.545

using lens maker formula,

1/f = (μ - 1)[1/R1 - 1/R2]

= (1.545 - 1)[1/40 - 1/-10 ]

= 0.545 × [1/40 + 4/40 ]

= 0.545 × 1/8

f = 8/0.545 = 14.67 cm

here no any option is 14.67 cm. so from approximation. we can say 15.55 cm might be correct choice.

also read similar questions: Rohit focused the image of a candle flame on a white screen using a convex lens.<br />

He noted down the position of the...

https://brainly.in/question/1558065

If radius of curvature is 10 cm then focal lenth of convex lens is

https://brainly.in/question/9705195

Answer 2

$\huge\bold\purple{Answer:-}$

d)15.55cm