Question

In displacement method the ratio of image heights is 9 : 4 if distance between the object and screen is 60 cm, then distance between the two positions of lens in cm is :

• A. 6
• B. 12
• C. 24
• D. 30

Answer 1

Answer: (B)

12

Answer 2

Let $D$ be the distance between the object and the screen, and $x$ be the distance between the two positions of the lens. The ratio of image heights is given as 9:4. Using the formula: $x = \frac{D}{5}$ Given $D = 60$ cm, $x = \frac{60}{5} = 12$ cm.