If the magnification of a virtual image formed of an object 10cm from a convex lens is 3, then the focal length of the lens is

JAMB 1980

If the magnification of a virtual image formed of an object 10cm from a convex lens is 3, then the focal length of the lens is

A. 10cm

B. 15cm

C. 16cm

D. 19cm

E. 20cm

Correct Answer: Option B

Explanation

V = 3u, U = 10cm

V = 10 × 3 =30cm

Since, we are dealing with a vertual image, V = -ve,

F = UV/(U+V)

= (10×(−30))/(10−30)

= 15cm

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About Teezab 1349 Articles
His Name is Tiamiyu Abdulbazeet Olawale. He is a student at the University of Ilorin studying Electrical and Electronics Engineering. He likes to give the latest updates about Nigeria and international institutions as he aims at helping people to lay their hands on the right information.

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