The power of the combination of a convex lens of focal length 50 cm and concave lens of focal length 40 cm is

Question

The power of the combination of a convex lens of focal length 50 cm and concave lens of focal length 40 cm is (A) + 1 D (B) - 1 D (C) zero (D) - 0.5 D

Tardigrade Admin · Accepted Answer

P=P1+P2 =(100/f1)+(100/f2), both f1 and f2 are in cm. =(100/50)-(100/40) =2-2.5=- 0.5 D

Q. The power of the combination of a convex lens of focal length 50 cm and concave lens of focal length 40 cm is

+ 1 D

- 1 D

zero

- 0.5 D

$P = P_{1} + P_{2}$ $= \frac{100}{f _{1}} + \frac{100}{f _{2}},$ both $f_{1}$ and $f_{2}$ are in cm. $= \frac{100}{50} - \frac{100}{40}$ $= 2 - 2.5 = - 0.5 D$

Q. The power of the combination of a convex lens of focal length 50 cm and concave lens of focal length 40 cm is

+ 1 D

- 1 D

zero

- 0.5 D

P=P1​+P2​ =f1​100​+f2​100​, both f1​ and f2​ are in cm. =50100​−40100​ =2−2.5=−0.5D

$P = P_{1} + P_{2}$ $= \frac{100}{f _{1}} + \frac{100}{f _{2}},$ both $f_{1}$ and $f_{2}$ are in cm. $= \frac{100}{50} - \frac{100}{40}$ $= 2 - 2.5 = - 0.5 D$