Question

a convex and concave lens of focal length 50cm and 40cm respectively are combined together. what is the power of combination​

Answer 1

Answer:

convex lens f = +40

cm as the principal

focal point is in the

direction of the rays.

concave lens = -50 cm

as the principal focal

point is on the side of

the object.

combination of thin

lenses: 1/f = 1/f1 + 1/

f2 = 1/40 - 1/50 =

1/200

f = 200 cm positive

so convex lens

P1 = 1 /(40/100) meter

= 2.5 Dioptre

P2 = 1/(-50/100)m = -2

D

power of combination

= P = P1 + P2 = 2.5 -

2.0 = 0.5 D

or, 1/

(200/100)m = 1/2 =

0.5 D

Explanation:

Answer 2

Answer:

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Explanation:

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