What is the focal length of a mirror if an object placed 21 cm from it produces an image that is magnified -0.85x? what is the power of the mirror?

focal length is 9.65 cm and the power is 10.36 diopter.

Explanation:

Now consider the case of concave mirror  according to sign convention

And the magnification produced buy it is,

Therefore,

Now focal length is,

Therefore the focal length is 9.65 cm.

Now, the power is,

Therefore,

Therefore the power of the mirror is is 10.36 diopter.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

answer: its c lololo