- #1
Rijad Hadzic
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Homework Statement
A sphere with a charge of -3.5 x 10^-9 C and a radius of 1.0x10^-2 m is located at the origin of a coordinate system.
What is the electric field 1.75 x 10^-2 m away from the center of the sphere along the positive y axis?
Homework Equations
e = kQ/r^2
The Attempt at a Solution
Ok so I plug in k and q
(8.99x10^9)(-3.5x10^-9) / r^2
Now for r^2, would the electric field strength be the distance of the coordinate in question, minus the radius of the sphere? I thought the electric field starts from the surface of the sphere?
My book plugged in value (1.75x10^-2) for the value of r, to reach their answer. But on first impression I thought I'm suppose to plug in value of .0075 for r.
Is this a mistake in my understanding or is the books answer wrong?