Question

Find magnification due to lens:

Given: \[ R_1 = 15\,\text{cm}, \quad R_2 = 12\,\text{cm}, \quad \text{Object distance } = 30\,\text{cm} \]

• A. \(m = +1\)
• B. \(m = -1\)
• C. \(m = +2\)
• D. \(m = -2\)

Hint:

A magnification with a {negative sign} means the image is inverted, and \(|m|>1\) indicates image magnification.

Answer 1

The Correct Option is D

Concept:
Magnification produced by a lens is given by: \[ m = \frac{v}{u} \] where \(u\) = object distance, \(v\) = image distance. Negative magnification indicates that the image is real and inverted
.
Step 1: Identify Object and Image Positions
From the given diagram:

Object is placed at \(u = -30\,\text{cm}\)
Image is formed at \(v = +60\,\text{cm}\)

Step 2: Calculate Magnification
\[ m = \frac{v}{u} = \frac{60}{-30} = -2 \] \[ \boxed{m = -2} \]