Problem 1: Two point charges are placed 2.0 cm apart. They are fixed in place so that they do not move.
a. A small ball of charge 3.0 x 10-9 C is placed at point A. the ball is small enough that it can be treated as a point charge.
What is the net electrical force excreted on the ball?
What is the electric field at point A (both magnitude and direction)?
b. How would your answer to part (a) change if the ball has a charge of -3.0 x 10-9 C? Explain.
c. How would your answer to part (a) for the electric field change if the ball had zero net charge? Explain.
Problem 2: Three point charges (A, B & C) are equally spaced along a line. Electric field lines around the changes are shown below.
a. One field line has an arrow on it to represent the direction of the force exerted on a positive test charge at any point on that line. Draw appropriate arrows on each of the other lines.
b. What do the field lines suggest about the approximate relative magnitudes of the three charges? Include information about the relative signs of the charges in your answer. Explain your reasoning.
c. Points 1, 2 and 3 are all equally far from charge B. rank the electric field at those poits in order by magnitude. (If the magnitude of the electric field is the same at two points, indicate that explicitly.) Explain your reasoning.
d. A positive test charge is moved along a straight line from A to B. Describe qualitatively how the force exerted by the electric field on that test charge would change as it moves along that line.
Problem 3: Shown below is a spherical sell with a uniformly distributed positive net charge on its surface.
a. Draw field lines to represent the electric field for this shell of charge.
b. Based on your drawing, what is the magnitude of the electric field inside the charged sphere? Explain your sphere? Explain your response.
