An object is placed at 20 cm in front of a concave mirror produces three time magnified real image. What is the position of the image from the concave mirror?

CONCEPT:

• Concave mirror: The mirror in which the rays converge after falling on it is known as the concave mirror.
  • Concave mirrors are also known as a converging mirror.
  • The focal length of a concave mirror is negative according to the sign convention.
• Magnification: In a concave mirror, the magnification is the ratio of the height of the image to the height of the object.
  • When the image is real, the magnification will be negative because the real image is inverted.
  • When the image is virtual, the magnification will be positive because the virtual image is erect.

 \(m = \frac{-v}{u}\)

where m is magnificent, v is the distance of the image from the mirror, and u is the distance of the object from the mirror.​

CALCULATION:

Given that u = -20 cm and m = -3.

\(m = \frac{-v}{u} \)

\(-3=\frac{-v}{-20}\)

v = -60 cm

So the correct answer is option 4.