Question 11

A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

Answer

Given:

Focal length of concave lens, f = −15 cm

Image distance, v = −10 cm

According to the lens formula,

The value of u is negative which shows that the object is placed 30 cm in front of the lens. The ray diagram is

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