CBSE Class 10 Sample Paper Science Solution - For 2023 Boards

A slide projector has a convex lens with a focal length of 20 cm. The slide is placed upside down 21 cm from the lens. How far away should the screen be placed from the slide projector’s lens so that the slide is in focus?



1/f= 1/v- 1/u

1/20 = 1/v- 1/-20

1/v = 1/20 - 1/21

= (21 - 20)/420

= 1/420

v= 420 cm

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo