Question

 A 3 cm tall object is placed 18 cm in front of a concave mirror of focal length 12 cm. At what distance from the mirror should a screen be placed to see a sharp image of the object on the screen. Also calculate the height of the image formed. 

Answer 1

here is your correct answer

Answer 2

Answer:

Explanation:

Given :-

u = - 18 cm

f = - 12 cm

To Find :-

u = ?

Image Height = ??

Solution :-

Using the mirror formula,

1/f = 1/v + 1/u

⇒ 1/v + 1/- 18 = 1/- 12

⇒ 1/v = - 1/12 + 1/18

⇒ 1/v = (-3 + 2)/36

⇒ 1/v = - 1/36

⇒ v = -36 cm

Magnification, m = - v/u

Also, m = h₁/h₂

⇒ m = - 36/- 18 = - 2

⇒- 2 = h₁/3

⇒ h₁ = - 6 cm

Hence, The image height will be 6 cm.