Aconcave makeup mirror is designed so the virtual image it produces is four times the size of the object when the distance between the object and the mirror is 18.0 cm. what is the radius of curvature of the mirror?

Radius of curvature = 48 cm.

Explanation:

Given that

Magnification,m=4

Distance between object and mirror,u=18 cm

We know that magnification of concave mirror given as

m= -v/u

So

4 = -v/18

v= - 72 cm

As we know that

f=24 cm

So r= 2 x f

r=48 cm

Radius of curvature = 48 cm.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.