Question

A convex lens produce a real and inverted image 2.5 times magnified at a distance of 25cm from the lens calculate a focal length and power of lens

Answer 1

Answer:

Explanation:

★ Magnification (m) = + 2.5

★ Image distance ( v ) = 25 cm

» We know that

→ Magnification = + V / U

→ U = V / 2.5

→→ U = 25 / 2.5 = 10cm

★ OBJECT DISTANCE = (-) 10cm

★ By Lens Formula :

» 1/ V - 1/ (-U) = 1/F

» 1 / 25 - 1 / (-10) = 1/F

» 1/25 + 1/10 = 1/F

» 10 + 25 / 250 = 1/ F

» F = 250 / 35 = 7.14 cm

ANSWER :- FOCAL LENGTH OF LENS IS 7.14 CENTIMETERS