Question

An object is placed at a distance of `20 cm` from a concave mirror of focal length `10 cm`. Find the position, magnification and nature of the image.

Answer 1

Answer:

You know the distance of the object from the mirror as well as the focal length.

Use the mirror formula as well as the formula for magnification to get the desired details.

Remember that a negative magnification indicates an inverted, real image and the positive magnification indicates and erect, virtual image.

Answer 2

Given:

$\sf{u=-20cm}$

$\sf{f=-10cm}$

$\sf{Mirror= Concave \:mirror}$

Solution:

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

$\sf{{\dfrac{1}{v}}=-{\dfrac{1}{10}}+{\dfrac{1}{20}}}$

$\sf{{\dfrac{1}{v}}=-{\dfrac{1}{20}}}$

$\sf{v=-20cm}$

$\bold{Magnification}$

$\sf{Magnification=}{\dfrac{-v}{u}}$

$\sf{Magnification=-}{\dfrac{-20}{-20}}$

$\sf{Magnification=-1}$

Thus the image formed will be real & inverted and of the same size as the object .The image will form at 'C'.