When an oject is placed 40 cm away from a spherical mirror an image of magnification is produced. To obtain an image with magnification of , the object is to be moved. [2025]

Question

When an object is placed 40 cm away from a spherical mirror an image of magnification $\frac{1}{2}$ is produced. To obtain an image with magnification of $\frac{1}{3}$ , the object is to be moved. [2025]

Smart Achievers · Accepted Answer

(1)

$m = \frac{1}{2} = \frac{f}{f - u} n$

$\frac{1}{2} = \frac{f}{f - (- 40)}$

$f + 40 = 2 f \Rightarrow f = 40 cm$

now $m = \frac{1}{3} = \frac{40}{40 - u}$

$40 - u = 120 \Rightarrow u = - 80 cm$

Move 40 cm away from mirror.

Solution

Q.
When an object is placed 40 cm away from a spherical mirror an image of magnification $\frac{1}{2}$ is produced. To obtain an image with magnification of $\frac{1}{3}$ , the object is to be moved. [2025]

1 40 cm away from the mirror.

2 80 cm away from the mirror.

3 20 cm towards the mirror.

4 20 cm away from the mirror.

Ans.
(1)

$m = \frac{1}{2} = \frac{f}{f - u} n$

$\frac{1}{2} = \frac{f}{f - (- 40)}$

$f + 40 = 2 f \Rightarrow f = 40 cm$

now $m = \frac{1}{3} = \frac{40}{40 - u}$

$40 - u = 120 \Rightarrow u = - 80 cm$

Move 40 cm away from mirror.

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