What is the focal length of a thin, flat piece of glass with no curvature?
I found that the power is 0 diopters, but I don't know what the focal length is.
Homework Statement
A 3.0mm-diameter copper ball is charged to 50nC.What fraction of its electrons have been removed? The density of copper is 8900kgm^3.
Homework Equations
d=m/v; v=4/3* pi r^3
The Attempt at a Solution
I worked through it and got 5.682 E -16, but that answer was...