A convex lens of power 5D is placed at a distance of 30 cm from a screen. At what distance from the lens should the screen be placed so that its image is formed on the screen? [3 MARKS]
Problem: 3 Marks
Power of the lens, P=+5D
Focal length, f = 15=0.2m=20cm
2. Here, the screen is placed 30 cm from the lens.
3. Using the lens formula, 1v−1u=1f
we get u=−60cm
Therefore, the screen should be placed at 60 cm from the lens.