Question

If a man's face is 20 cm in front of concave shaving mirror producing erect image 1.5cm times the size of face , focal length of the mirror would be A)75 cm B) 25 cm C) 15 cm D) -60 cm

Answer 1

Answer:

- 60 cm

Explanation:

Focal length,f=?

object distance is= - 20 cm

Magnification,1.5 = - v ÷ - 20

v= 30 cm

using the mirror formulae

1÷ v + 1 ÷ u = 1 ÷ F

1 ÷ 30 - 1 ÷ 20 = 1 ÷ F

2-3 ÷ 60 = 1 ÷ F = F = - 60 cm...

Hope this answer helps u...✌✌✌