Question

A concave mirror produces 10cm long image of an object of height of 4cm.What is the magnification

produced ?

also mention where does the negative sign requires and why ???​

Answer 1

* In case of height given of object and image..the formula for finding magnification is:

Height of image/ Height of object.

*The height of object is always taken as positive and written with a plus sign as it is always placed above the principal axis.

* Now, if the image of that object formed by a concave mirror is real, it is formed below the axis. so the height of a real image is taken as negative and written with a minus sign.

* But..if the image of that object formed by a concave mirror is virtual, it is formed above the principal axis. so the height of a virtual image is taken as positive and written with a positive sign.

Explanation:

solution: ( If image is real)*

Height of object, h1= +4 cm

Height of image, h2= -10 cm

Then, we know that:

Magnification= Height of image/ Height of object

or, m= h2/h1

so, m= -10/+4

m= -2.5

Hence, magnification produced= -2.5