WAEC Physics 2013 Objective — Question 29

Question 29 of 50 from the West African Examinations Council (WAEC) Physics 2013 Objective paper, with the correct answer and a full explanation.

A diverging lens of focal length 30cm produces an image 20cm from the lens. Determine the object distance.

Explanation

For a diverging lens, f=−30cm, v=−20cm (virtual image). Using 1/f = 1/u + 1/v: −1/30 = 1/u − 1/20; 1/u = 1/30+1/20 = 0.0167; u = 60cm.

…and/or go further with premium services and No Ads.