Question

Figure given below shows a beam of light converging at point P. When a concave lens of focal length 16 cm is introduced in the path of the beam at a place O shown by dotted line such that OP becomes the axis of the lens, the beam converges at a distance x from the lens. The value x will be equal to

• A. 12 cm
• B. 24 cm
• C. 36 cm
• D. 48 cm

Answer 1

Answer: (D)

48 cm

Answer 2

From the figure shown it is clear that

For lens : u = 12 cm and v = x = ?

By using $\frac { 1 } { f } = \frac { 1 } { v } - \frac { 1 } { u }$

⇒ $\frac { 1 } { + 16 } = \frac { 1 } { x } - \frac { 1 } { + 12 }$ ⇒ x = 48 cm