Two lenses of power +12 and -2 dioptres are placed in contact. The combined focal length of the combination will be

Question

Two lenses of power +12 and -2 dioptres are placed in contact. The combined focal length of the combination will be (A) 8.33 cm (B) 1.66 cm (C) 12.5 cm (D) 10 cm

Tardigrade Admin · Accepted Answer

P=P1+P2 =+12-2=10 D Now F=(1/P)=(1/10) m=10 cm .

Q. Two lenses of power $+ 12$ and $- 2$ dioptres are placed in contact. The combined focal length of the combination will be

8.33 cm

1.66 cm

12.5 cm

10 cm

$P = P_{1} + P_{2}$
$= + 12 - 2 = 10 D$
Now $F = \frac{1}{P} = \frac{1}{10} m = 10 c m .$

Q. Two lenses of power +12 and −2 dioptres are placed in contact. The combined focal length of the combination will be