A converging lens of focal length 5cm forms a virtual image which is 10cm from the lens. How far from the lens is the object?

A. 2.0cm
B. 3.3cm
C. 5.0cm
D. 10.0cm
E. 15.0cm

Correct Answer:

Option B – 3.3cm

Explanation

f = uv/(u+v)

5 = −10u/(−10+u)

50+5u = −10u

50 = −10u−5u

u = 50/−15

u= -3.3cm