Navigate

An object is placed 30 cm away from a convex lens of focal length 10 cm and a sharp

An object is placed 30 cm away from a convex lens of focal length 10 cm and a sharp image is formed on a screen. Now, a concave lens is placed in contact with the convex lens. The screen now has to be moved by 45 cm to get a sharp image again. The magnitude of focal length of the concave lens is (in cm)

Options

(a) 72
(b) 60
(c) 36
(d) 20

Correct Answer:

20

Explanation:

No explanation available. Be the first to write the explanation for this question by commenting below.

WB2014
admin:

Related Questions

  1. Three blocks A,B and C of masses 4 kg, 2 kg and 1 kg respectively are in contact
  2. The ratio of volumes of nuclei (assumed to be in spherical shape) with respective
  3. A source of light is placed at a distance of 50 cm from a photocell and the stopping
  4. An ideal heat engine works between temperature T₁=500 K and T₂=375 K.
  5. A bullet loses 1/20 of its velocity after penetrating a plank.How many planks