Question

A biconvex lens has a radius of curvature of magnitude 20cm. Which of the following options best describe the image formed of an object of height 2cm placed 30cm from the lens?

• A. Virtual, upright, height = 1cm
• B. Virtual, upright, height = 0.5cm
• C. Real, inverted, height = 4cm
• D. Real, inverted, height = 1cm

Hint:

For convex lenses, objects beyond focus form real, inverted images.

Answer 1

The Correct Option is D

Step 1: Lens maker formula (assuming glass): (1)/(f) = (1)/(20) + (1)/(20) = (1)/(10) ⟹ f = 10cm
Step 2: Lens formula: (1)/(v) - (1)/(u) = (1)/(f) ⟹ v = 15cm
Step 3: Magnification: m = (v)/(u) = (15)/(30) = (1)/(2) ⟹ hᵢ = 1cm