Abington Heights High School
AP Physics
Electrostatic Potential Quiz 4
Select the answer that best completes the question.
1. Which one of the following changes will necessarily increase the capacitance of a capacitor?
A.decreasing the charge on the plates
B.increasing the charge on the plates
C.placing a dielectric between the plates
D.increasing the potential difference between the plates
E.decreasing the potential difference between the plates
2. When a dielectric with constant k is inserted between the plates of a charged isolated capacitor
A.the capacitance is reduced by a factor k.
B.the charge on the plates is reduced by a factor of k.
C.the charge on the plates is increased by a factor of k.
D.the electric field between the plates is reduced by a factor of k.
E.the potential difference between the plates is increased by a factor of k.
3. A parallel plate capacitor has a potential difference between its plates of 1.2 V and a plate separation distance of 2.0 mm. What is the magnitude of the electric field if a material that has a dielectric constant of 3.3 is inserted between the plates?
A.75 V/m
B.180 V/m
C.250 V/m
D.400 V/m
E.500 V/m
4. A capacitor has a very large capacitance of 10 F. The capacitor is charged by placing a potential difference of 2 V between its plates. How much energy is stored in the capacitor?
A.2000 J
B.500 J
C.100 J
D.40 J
E.20 J
5. The effective area of each plate of a parallel plate capacitor is 2.4 m2. The capacitor is filled with neoprene rubber (k = 6.4). When a 3.0-V potential difference exists across the plates of the capacitor, the capacitor stores 5.0 µC of charge. Determine the plate separation of the capacitor.
A.7.2 ´ 10-5 m
B.3.0 ´ 10-4 m
C.1.7 ´ 10-4 m
D.5.3 ´ 10-4 m
E.8.2 ´ 10-5 m
6. A uniform electric field of 8 V/m exists between the plates of a parallel plate capacitor. How much work is required to move a +20 mC point charge from the negative plate to the positive plate if the plate separation is 0.050 m?
A.0.4 J
B.1.6 J
C.8 ´ 10-4 J
D.8 ´ 10-5 J
E.8 ´ 10-6 J
7. A capacitor is initially charged to 2 V. It is then connected to a 4 V battery. What is the ratio of the final to the initial energy stored in the capacitor?
A.2
B.4
C.6
D.8
E.10
8. A parallel plate capacitor has plates of area 2.0 ´ 10-3 m2 and plate separation
1.0 ´ 10-4 m. Determine the capacitance of this system if air fills the volume between the plates.
A.1.1 ´ 10-10 F
B.1.8 ´ 10-10 F
C.3.2 ´ 10-10 F
D.4.4 ´ 10-10 F
E.5.3 ´ 10-10 F
9. A parallel plate capacitor has plates of area 2.0 ´ 10-3 m2 and plate separation 1.0 ´ 10-4 m. Air fills the volume between the plates. What potential difference is required to establish a charge of 3.0 mC on the plates?
A.9.3 ´ 102 V
B.2.4 ´ 104 V
C.1.7 ´ 104 V
D.6.9 ´ 103 V
E.3.7 ´ 105 V
10. A potential difference of 120 V is established between two parallel metal plates. The magnitude of the charge on each plate is 0.020 C. What is the capacitance of this capacitor?
A.170 µC
B.24 µC
C.7.2 µC
D.0.12 C
E.2.4 C
11.
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
R-1 Ref 19-8

Determine the magnitude of the electric field between the capacitor plates.
A.60 V/m
B.120 V/m
C.1.0 ´ 105 V/m
D.1.5 ´ 105 V/m
E.3.0 ´ 105 V/m

12.
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
R-1 Ref 19-8

Determine the value of the capacitance.
A.9.0 ´ 10-11 F
B.1.8 ´ 10-10 F
C.3.6 ´ 10-10 F
D.4.8 ´ 10-10 F
E.6.4 ´ 10-10 F

13.
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
R-1 Ref 19-8

Determine the magnitude of the charge on either capacitor plate.
A.1.8 ´ 10-7 C
B.2.7 ´ 10-7 C
C.4.9 ´ 10-7 C
D.5.4 ´ 10-7 C
E.6.8 ´ 10-7 C

14.
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
R-1 Ref 19-8

How much work is required to move a -4 mC charge from the negative plate to the positive plate of this system?
A.-1.2 ´ 10-2 J
B.+1.2 ´ 10-2 J
C.-2.4 ´ 10-2 J
D.+2.4 ´ 10-2 J
E.-5.4 ´ 10-2 J

15.
The plates of a parallel plate capacitor each have an area of 0.40 m2 and are separated by a distance of 0.02 m. They are charged until the potential difference between the plates is 3000 V. The charged capacitor is then isolated.
R-1 Ref 19-8

Suppose that a dielectric sheet is inserted to completely fill the space between the plates and the potential difference between the plates drops to 1000 V. What is the capacitance of the system after the dielectric is inserted?
A.1.8 ´ 10-10 F
B.2.7 ´ 10-10 F
C.5.4 ´ 10-10 F
D.6.2 ´ 10-10 F
E.6.8 ´ 10-10 F


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