Question

If distance between virtual image from its real object is 60 cm in case of a concave mirror. Calculate focal length of concave mirror if image formed is 3 times magnified –

• A.
  • 15 cm
• B. – 15 cm
• C.
  • 22.5 cm
• D. – 22.5 cm

Answer 1

Answer: (D)

– 22.5 cm

Answer 2

x + 3x = 60 Ž x = 15 cm

u = – 15 cm

m = + 3

\ m = $\frac { \mathrm { f } } { \mathrm { f } - \mathrm { u } }$ Ž + 3 =

\ 3f + 45 = f Ž f = – 22.5 cm