ExamBro
ExamBro
CUET · PHYSICS · PYQ PAPER 2023

Two thin lenses are in contact and the focal length of the combination is 60 cm. If the focal length of one lens is 20 cm, the focal length of the other would be :

  1. A 60 cm
  2. B - 30 cm
  3. C 20 cm
  4. D 15 cm
Verified Solution

Answer & Solution

Correct Answer

(B) - 30 cm

Step-by-step Solution

Detailed explanation

\( \frac{1}{F} = \frac{1}{f_1} + \frac{1}{f_2} \) \( \frac{1}{60} = \frac{1}{20} + \frac{1}{f_2} \) \( \frac{1}{f_2} = \frac{1}{60} - \frac{1}{20} = \frac{1 - 3}{60} = -\frac{2}{60} = -\frac{1}{30} \) \( f_2 = -30 \) cm
Same subject
Explore more questions on app