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
waec 1996physics

The correct answer is B. 3.3cm

\(f = \frac{uv}{u+v}\)

\(5 = \frac{-10u}{-10+u}\)

\(50 + 5u = -10u\)

\(50 = -10u - 5u\)

\(u = \frac{50}{-15}\)

u= -3.3cm

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