Question

Numerical problem.

A concave mirror produces three times magnified real image of an object placed at 7 cm in front of it. Where is the image located? (Ans: 21 cm in front of the mirror)

Answer 1

Given: h_i = 3h_o
u = 7 cm
Solution:

1. m = ${\displaystyle \frac{{\text{h}}_{\text{i}}}{{\text{h}}_{\text{O}}}\Rightarrow \frac{3{\text{h}}_{\text{o}}}{{\text{h}}_{\text{O}}}}$ ∴ m = 3.
2. 
   m = ${\displaystyle –\frac{v}{u}}$
   v = – m × u
   = – 3 × 7 cm = – 21 cm.
   Hence, Real, inverted and magnified image will be formed at 21 cm in front of the mirror.