Screen and object are placed at distance of 100 cm along a straight line a lens produces an image on the screen when placed at either positions 50 cm apart the focal length of the lens is
Answers
the focal length of lens is 18.75 cm
It is given that screen and object are placed at the distance of 100cm along a straight line a lens produces an image on the screen when placed at either position 50cm apart.
we have to find the focal length of the lens.
here u + v = 100 cm , u - v = 50 cm
after solving we get, u = 75cm, v = 25cm
including sign convention,
u = -75 cm , v = +25 cm
now using lens maker formula,
1/v - 1/u = 1/f
⇒1/25 + 1/75 = 1/f
⇒4/75 = 1/f
⇒f = 75/4 = 18.75 cm
therefore, the focal length of lens is 18.75 cm
Answer:
we have to find the focal length of the lens.
here u + v = 100 cm , u - v = 50 cm
after solving we get, u = 75cm, v = 25cm
including sign convention,
u = -75 cm , v = +25 cm
now using lens maker formula,
1/v - 1/u = 1/f
⇒1/25 + 1/75 = 1/f
⇒4/75 = 1/f
⇒f = 75/4 = 18.75 cm