Question

What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm ?

Answer 1

Answer:

Hence the position of image will be at infinity means the position is indefinite. Originally Answered: What is the position of an image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm? When an object is placed on the focus of a concave mirror the image is formed at infinity.

Answer 2

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$\huge {\underline {\mathfrak { Question }}}$

What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm ?

$\huge{\underline {\mathfrak { Given}}}$

• Object distance ( u ) = -20cm

• Focal length ( f ) = -20cm ( concave mirror )

$\huge {\underline {\mathfrak { To \: find}}}$

• Image distance ( v )

$\huge{\underline {\mathfrak { Formula }}}$

Mirror formula

• ${\huge {\boxed {\tt { \frac {1}{v} + \frac {1}{u}= \frac {1}{f} }}} }$

Where,

• v = image distance
• u = object distance
• f = focal length

$\huge {\underline {\mathfrak { Calculation }}}$

According to mirror formula,substituting values-

$☞ \sf\red { \frac{1}{v} + \frac{1}{u} = \frac{1}{f}}$

$☞ \sf { \frac{1}{v} + \frac{1}{( - 20)} = \frac{1}{( - 20)}}$

$☞ \sf { \frac{1}{v} = - \frac{1}{ 20} + \frac{1}{20} }$

$☞ \sf { \frac{1}{v } = 0}$

$☞\sf\red { \therefore \: v = infinty}$

$\huge {\underline {\mathfrak { Final \: answer }}}$

The position of the image will be at infinity.

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