Mirrors And Images

We use the mirror equation to solve for the image distance

v

%5Cfrac%7B1%7D%7Bf%7D%20%3D%20%5Cfrac%7B1%7D%7Bu%7D%20%2B%20%5Cfrac%7B1%7D%7Bv%7D

Where: -

f%20%3D%2015%20%5C%2C%20%5Ctext%7Bcm%7D

(focal length of the concave mirror) -

u%20%3D%20-25%20%5C%2C%20%5Ctext%7Bcm%7D

(object distance, negative for real objects placed in front of the mirror) Substitute these values into the equation:

%5Cfrac%7B1%7D%7B15%7D%20%3D%20%5Cfrac%7B1%7D%7B-25%7D%20%2B%20%5Cfrac%7B1%7D%7Bv%7D

Solve for

v

%5Cfrac%7B1%7D%7Bv%7D%20%3D%20%5Cfrac%7B1%7D%7B15%7D%20%2B%20%5Cfrac%7B1%7D%7B25%7D%20%3D%20%5Cfrac%7B5%20%2B%203%7D%7B75%7D%20%3D%20%5Cfrac%7B8%7D%7B75%7D

v%20%3D%20%5Cfrac%7B75%7D%7B8%7D%20%3D%209.375%20%5C%2C%20%5Ctext%7Bcm%7D

Thus, the image will form at

-35.5%20%5C%2C%20%5Ctext%7Bcm%7D

, meaning the screen must be placed at this position to get a sharp image.

Chapter Questions
1 MCQs