Question

solve questions no 11​

Answer 1

Answer:

The card will be placed at 30 cm away from mirror.

The image formed will be inverted, magnified and real.

The height of the image will be 4 cm.

Explanation:

The experiment of lens and sun tells about the focal length ($f$) of the mirror.

Hence, the focal length is $f$ = 10 cm.

Now, mirror formula is

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

 $f=-10~cm\\u=-15~cm\\v=?$

Putting these values,

${1\over -10}={1\over-15}+{1\over v}\\\\{1\over v}={1\over 15}-{1\over 10}\\\\{1\over v}={-1\over 30}\\\\v=-30~cm$

This tells the image distance, here, -ve sign tells that the image is real.

Now, Since, magnification ($m$) is given by

$m={-v\over u}\\\\m={-(-30)\over-15}\\\\m=-2$

Since, magnitude of m is greater than one, hence image will be enlarged. Negative sign here tells that the image is inverted.

Also,

$m={Image~height\over Object~height}\\\\Image~height=m\times Object~height\\\\Image~height=-2\times2~cm=-4~cm$