Download Chapter 24 - KFUPM Faculty List

PHYS 102 – Quiz Problems
Chapter 24 : Electric Potential
Dr. M. F. Al-Kuhaili
1. (TERM 001)
Two point charges Q1 = + 5.00 nC and Q2 = - 3.00 nC are separated by 35.0 cm.
(a) What is the potential energy of the pair?
(b) What is the significance of the algebraic sign of your answer?
(c) What is the electric potential at a point midway between the charges?
2. (TERM 001)
How much work is required to assemble four identical charges (q = 0.50 µC) on the vertices of a square of side 0.10 m?
3. (TERM 002)
Two parallel plates having equal but opposite charge are separated by 12.0 cm. Each plate has a surface charge density of
36.0 nC/m2. A proton is released from rest at the positive plate.
(a) Calculate the electric field in the region between the plates.
(b) Calculate the potential difference between the plates.
(c) Calculate the acceleration of the proton.
(d) Calculate the energy of the proton when it reaches the negative plate.
4. (TERM 002)
An electron moving parallel to the x – axis has an initial speed of 3.7 × 106 m/s at the origin. Its speed is reduced to 1.4 ×
105 m/s at the point x = 2.0 cm.
(a) Calculate the potential difference (magnitude and sign) between the origin and this point.
(b) Which point is at a higher potential?
(c) What is the direction of the electric field, and why?
5. (TERM 012)
In the figure: q1 = + 2.0 µC and q2 = – 3.0 µC. How much work must be done by an external force to move a third charge
q3 = + 2.5 µC from A to B? Take V = 0 at infinity.
6. (TERM 012)
In the figure, what is the net electric potential at point P due to the four point charges? Take q = 1.0 nC and d = 5.0 m.
7. (TERM 012)
The electric potential at points in an xy plane is given by V = 2.0 x2 – 3.0 y2, where V is in volts, x and y are in meters.
What are the magnitude and direction of the electric field at the point (3.0, 2.0)?
8. (TERM 021)
What potential difference (magnitude only) is needed to stop an electron having an initial speed of 4.2 x 105 m/s?
9. (TERM 021)
Consider two points in an electric field: The potential at P1 is V1 = – 30.0 V, and the potential at P2 is V2 = + 150 V.
How much work (magnitude and sign) is done by an external force in moving a point charge q = – 4.70 µC from P2 to P1?
10. (TERM 022)
Consider two points in an electric field. The electric potential at P1 is V1 = – 20 V, and the electric potential at P2 is
V2 = + 180 V. If an electron moves from point 2 to point 1, what is the change in its electric potential energy?
11. (TERM 022)
The figure shows two charged particles on the x-axis separated by a distance of 1.0 m. The particles have charges q1 = +
1.0 µC and q2 = – 3.0 µC. Find the point on the x-axis, between q1 and q2, at which the electric potential is zero.
12. (TERM 022)
Two electrons are fixed a distance of 1.00 nm apart on the x-axis. How much work must an external agent do to bring a
third electron from infinity and place it midway between the two electrons?
13. (TERM 033)
The figure below shows a proton moving from point A to point B in a direction that is anti-parallel to a uniform electric
field that has a magnitude of 4.2 × 104 N/C. If the distance from A to B is 0.18 m, what is the change in the proton’s
electric potential energy UB – UA? The proton is at rest at A and B.
14. (TERM 042)
Two particles of charges q and q are separated by a distance of 0.010 m, as shown in the figure.
1
2
q1 = + 2.8 nC and q2 = – 2.8 nC.
(a) What is the electric potential due to q1 and q2 at point A?
(b) What is the electric potential due to q1 and q2 at point B?
(c) An electron is moved form rest at A to rest at B, what is the change in its electric potential energy?
15. (TERM 042)
Two point charges q1 = + 2.4 nC and q2 = – 6.5 nC are 0.10 m apart.
(a) Find the electric potential due to q1 and q2 at point A.
(b) Find the electric potential due to q1 and q2 at point B.
(c) A third charge q3 = + 2.5 nC travels from B to A. Find the work done by the electric field on q .
3
16. (TERM 042)
A point charge q = + 1.0 µC is moved from point P to point Q in a uniform electric field directed to the left, as shown in
the figure below. The magnitude of the work done by the electric field on the charge q is 9.0 µJ.
(a) Is the work done by the electric field positive or negative?
(b) Does the electric potential energy of the charge q increase or decrease?
(c) What is the electric potential difference VQ – VP?
(d) What is the magnitude of the electric field?
17. (TERM 052)
G
A uniform electric field is given by: E = 12ˆi (N/C). An electron moves along the x axis from point A (x = + 3.0 cm) to
point B (x = + 6.0 cm).
(a) What is the potential difference VA – VB?
(b) What is the change in the electric potential energy of the electron?
18. (TERM 052)
In the figure: q1 = + 3.0 µC and q2 = – 5.0 µC.
(a) What is the electric potential at point A due to the two point charges?
(b) What is the electric potential at point B due to the two point charges?
(c) How much work must be done by an external force to move a third charge q3 = + 2.5 µC from A to B?
19. (TERM 052)
Consider a point P which is a distance R away from a point charge Q. At point P, the electric field is 150 N/C pointing
radially outward, and the electric potential is 420 V. Determine the values of Q and R.
20. (TERM 061)
What is the external work required to bring three charges from infinity and place them at the corners of an equilateral
triangle of side length 0.20 m? All charges are negative, and each charge has a magnitude of 2.5 µC.
21. (TERM 061)
G
Points A [at (–4 , –6) m] and B [at (5 , 7) m] are in a region where the electric field is given by: E = −400ˆj (N/C).
What is the electric potential difference VA – VB?
22. (TERM 061)
In an electric field, the electric potential at point A is 12 V smaller than the electric potential at point B. If a charge
Q = – 3.5 µC is moved from B to A, what is the change in the electric potential energy of the charge?
23. (TERM 062)
Point A has coordinates (1,5) m and point B has coordinates (5,1) m. These two points are in a uniform electric field:
G
E = 15ˆj (N/C). What is the electric potential difference VA – VB?
24. (TERM 062)
Three point charges are: q1 = + 1.5 µC, q2 = + 2.5 µC, and q3 = – 3.5 µC.
What is the external work required to bring these three charges from infinity and place them at the corners of an
equilateral triangle of side length 0.20 m?
25. (TERM 062)
A charge of 1.5 µC is distributed uniformly over the surface of a solid conducting sphere of radius R = 7.5 cm. Point A is
a distance of 5.0 cm from the center of the sphere, and point B is a distance of 9.0 cm from the center of the sphere.
(a) What is the electric potential at point A?
(b) What is the electric potential at point B?
26. (TERM 063)
Two point charges Q1 = + 5.0 nC and Q2 = – 3.0 nC are fixed on the x axis with Q1 at the origin and Q2 at x = + 45 cm.
(a) What is the electric potential at x = – 35 cm?
(b) What is the electric potential energy of the two charges?
27. (TERM 063)
Three point charges –Q, –Q, and +3Q are arranged along a line as shown in the figure. What is the electric potential at
point P? (Q = 10-6 C and R = 5.0 cm)
P
R
−Q
−Q
+3Q
R
R
28. (TERM 071)
The electric potential at point A is VA = + 60 V, and that at point B is VB = + 20 V.
A charge q = + 6.0 µC is moved from A to B.
What is the change in the electric potential energy of the charge?
29. (TERM 071)
Two parallel plates are separated by 0.30 mm. The potential difference between them is 20 V.
Calculate the magnitude of the electric field between the plates.
30. (TERM 071)
Two point charges, Q1 = + 5.00 nC and Q2 = – 3.00 nC, are separated by a distance of 0.35 m. What is the electrical
potential at a point midway between the charges?