Question

A student focused the image of a candle flame on a white screen using a lens. He noted down the position of the candle screen and the lens as mentioned below:
Position of candle = 12.0 cm
Position of lens = 50.0 cm
Position of the screen = 88.0 cm

(iii) What is the nature of the image? Is it enlarged?

• A. Virtual, Enlarged
• B. Real, Enlarged
• C. Real, Diminished
• D. Real, Same size

Answer 1

The correct option is D Real, Same size

Given:
Position of candle = 12.0 cm
Position of lens = 50.0 cm
Position of the screen = 88.0 cm

Measuring all the distances from the pole, we get:
Object distance, $u=12-50=-38cm$
Image distance, $v=88-50=+38cm$

Since the image is formed on the other side of the lens, it is real.

Using formula of magnification,
$m=\frac{v}{u}$
$m=\frac{+38}{-38}=-1$

Magnification of $-1$ suggests that the image is inverted and the same size as that of the object.