Question

an object of size 70 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm at what distance from a mirror should a screen be placed so that a sharp focused image can be obtained​

Answer 1

Given:

• Size of object = Ho = 70cm
• Object distance = u = -27cm
• Focal length = f = -18cm

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Need to find:

• Distance at which the screen will be placed from the mirror = v = ?

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Solution:-

We know,

$\dfrac{1}{v} + \dfrac{1}{u} = \dfrac{1}{f}$

$\implies \dfrac{1}{v} + \dfrac{1}{-27} = \ffrac{1}{-18}$

$\implies \dfrac{1}{v} = \dfrac{1}{-18} \dfrac{1}{27}$

$\implies \dfrac{1}{v} = \dfrac{1}{27} - \dfrac{1}{18}$

$\red{\bold{\boxed {\large{\implies \dfrac{1}{v} = - 54 cm}}}}$

$\therefore$ The screen should be placed 54cm infront of the mirror.

The image will be real.

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Answer 2

Answer:

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Explanation: