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AP Electrostatics Homework
1.
Find the net charge of a system consisting of each of the following.
(a) 5.89 106 electrons and 7.23 106 protons
C
(b) 241 electrons and 161 protons
C
2.
In the Bohr model, the electron is imagined to move in a circular orbit about a stationary proton.
If the speed of the electron were 7.5 105 m/s, what would be the corresponding orbital radius?
m
3.
Find the direction and magnitude of the net electrostatic force exerted on the point charge q2 in
the figure below. Let q = +1.5 µC and d = 29 cm.
Direction
° (from the x-axis, which points to the right)
Magnitude
N
4.
What is the magnitude of the electric field produced by a charge of magnitude 3.05 µC at each of
the following distances?
(a) 1.07 m
N/C
(b) 2.43 m
N/C
5.
The electric field between the plates of a parallel-plate capacitor is horizontal, uniform and has a
magnitude E. A small object with a charge of -2.70 µC is attached to the string. Assume that the
tension in the string is 0.350 N, and the angle it makes with the vertical is 15°.
(a) What is the mass of the object?
g
(b) What is the magnitude of the electric field?
N/C
6.
A proton is released from rest in a uniform electric field of magnitude +1.51 105 N/C. Find the
speed of the proton after it has traveled each of the following distances.
(a) 7.00 cm
m/s
(b) 70.0 cm
m/s
7.
Two small plastic balls hang from threads of negligible mass. Each ball has a mass of 0.46 g and
a charge of magnitude q. The balls are attracted to each other, and the threads attached to the
balls make an angle of 20.0° with the vertical, as shown in the figure below.
(a) Find the magnitude of the electric force acting on each ball.
N
(b) Find the tension in each of the threads.
N
(c) Find the magnitude of the charge on the balls.
C
8.
The figure below shows an electron entering a parallel-plate capacitor with a speed of v = 5.70
106 m/s. The electric field of the capacitor has deflected the electron downward by a distance of
d = 0.598 cm at the point where the electron exits the capacitor.
(a) Find the magnitude of the electric field in the capacitor.
N/C
(b) Find the speed of the electron when it exits the capacitor.
m/s
9. Question Details Walker3 20.P.009. [565787]
Question part
Points
1 2 3
-- -- -Total
0/3
A uniform electric field with a magnitude of 6690 N/C points in the positive x direction. Find the
change in electric potential energy when a +12.5 µC charge is moved 5.66 cm in the following
directions.
(a) the positive x direction
mJ
(b) the negative x direction
mJ
(c) the positive y direction
mJ
10.
The electric potential 2.3 m from a point charge q is 2.7 104 V. What is the value of q?
µC
11.
A parallel-plate capacitor is made from two aluminum-foil sheets, each 3.0 cm wide and 5.00 m
long. Between the sheets is a Teflon strip of the same width and length that is 0.024 mm thick.
What is the capacitance of this capacitor? (The dielectric constant of Teflon is 2.1.)
µF
12.
An automatic external defibrillator (AED) delivers 145 J of energy at a voltage of 850 V. What is
the capacitance of this device?
µF
13.
A point charge of mass 0.075 kg and charge q = +5.78 µC is suspended by a thread between the
vertical parallel plates of a parallel-plate capacitor, as shown in the figure below.
(a) If the charge deflects to the right of vertical, as indicated in the figure, which of the two plates
is at the higher electric potential?
right plate
left plate
(b) If the angle of deflection is 22°, and the separation between the plates is 0.025 m, what is the
potential difference between the plates?
kV