What is the focal length of concave mirror that magnifies , by a factor of +3.2 , an object that is placed 30cm from the mirror?

23 cm

Explanation:

The formula for magnification is;

Magnification = image distance / object distance

use values as;

3.2 = v / 30   where v is image distance

v =30*3.2

v=96 cm

The relationship of the focal length with image distance and object distance is expressed as;

where f is the focal length and u is object distance

use values in the equation as;

f=160/7

f=22.86

f= 23 cm ----------nearest a cm

explanation:

an enlarged virtual image is the answer

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?