Practice: A 1.5uC charge, with a mass of 50g, is in the presence of an electric field that perfectly balances its gravity. What magnitude does the electric field need to be, and in what direction does it need to point?
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Practice: If two equal charges are separated by some distance, they form an electric dipole. Find the electric field at the center of an electric dipole, given by the point P in the following figure, formed by a 1C and a – 1C charge separated by 1 cm.
Practice: 4 charges are arranged as shown in the following figure. Find the electric field at the center of the arrangement, indicated by the point P.
Practice: In the following figure, a mass m is balanced such that its tether is perfectly horizontal. If the mass is m and the angle of the electric field is 𝜃, what is the magnitude of the electric field, E?
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Videos in Electric Field
Concept #1: Intro to Electric Fields
Practice #1: Balancing Gravity
Concept #2: Electric Field due to a Point Charge
Example #1: Zero Electric Field due to Two Charges
Practice #2: Electric Field at Center of Dipole
Example #2: Electric Field Above Two Charges (Triangle)
Practice #3: Electric Field at Center of Four Charges
Example #3: Balancing a Pendulum in Electric Field
Practice #4: Balance Mass in Electric Field (Angled)
Additional Problems
An electron traveling along the +x-axis enters an electric field that is directed vertically down, i.e., along the negative y-axis. What will be the direction of the electric force acting on the electron after entering the electric field?
A) -y
B) +y
C) +x
D) -x
Four identical point charges, q, are placed at the corners of a square. Each side of the square has length L. What is the magnitude of the electric field at the point P, the center of the square?
A) 0
B) kq2/L2
C) kq2/2L2
D) kq2/4L2
In the figure, point B is a distance L away from a point charge Q. Point A is a distance 4L away from Q. What is the ratio of the electric field at A to that at B, EA/EB?
A) 1/16
B) 1/9
C) 1/4
D) 1/3
E) This cannot be determined
The four charges form a square of edge length a. What is the direction of the net electric field at the square's center?
a. -x
b. +x
c. +y
d. -y
e. The field is zero at the center.
A charged particle traveling along the +x axis enters an electric field directed vertically upward along the +y axis. If the charged particle experiences a force downward because of this field, what is the sign of the charge on this particle?
A) It is neutral.
B) It is positive.
C) It is negative.
D) None of previous is correct.
Two charges, q1 = -2.50 nC and q 2 = +2.00 nC, are placed 0.400 m apart as shown in the figure. What is the magnitude of the electric field at point P, 0.300 m above q 2?
A) 71.9 N/C
B) 218 N/C
C) 53.9 N/C
D) 163 N/C
E) 146 N/C
Two charges, q1 = -2.50 nC and q 2 = +2.00 nC, are placed 0.400 m apart as shown in the figure. What is the direction of the electric field at point P, 0.300 m above q 2?
A) 116° counter-clockwise from the positive x-axis.
B) 63.7° clockwise from the positive x-axis.
C) 72.4° counter-clockwise from the positive x-axis.
D) 108° clockwise from the positive x-axis.
E) 90° counter-clockwise from the positive x-axis.
Two charged particles are located at x = -a and x = +a, as shown below, on the x-axis. The electric field produced by these two charges at any point on the y-axis, is always
A) in the +y direction
B) in the -y direction
C) in the +x direction
D) in the -x direction
An electron traveling horizontally at 6 × 10 6 m/s enters a 0.05 m region with a uniform electric field of 89 N/C , perpendicular to the electron's velocity. The mass of an electron is 9.10939 × 10−31 kg and the charge on an electron is 1.60218 × 10−19 C . What is the magnitude of the vertical displacement ∆y of the electron while it is in the electric field?
1. 0.00485434
2. 0.000543524
3. 0.0148796
4. 0.0649004
5. 0.00403356
6. 0.000873782
7. 0.00354891
8. 0.0176498
9. 0.00427393
10. 0.00586273
A charge of 3 μC is at the origin. Sketch the function E x versus x for both positive and negative values of x. (Remember that Ex is negative when E points in the negative x direction.)
The figure shows two unequal point charges, q and Q, of opposite sign. Charge Q has greater magnitude than charge q. In which of the regions X, Y, Z will there be a point at which the net electric field due to these two charges is zero?(a) only region X(b) only regions X and Z(c) only region Y(d) only region Z(e) all three regions
An electron traveling along the +x-axis enters an electric field that is directed vertically down, i.e. along the negative y-axis. What will be the direction of the electric force acting on the electron after entering field?A) downwardB) upwardC) to the leftD) to the right
In the four configurations of charges, all the charges are the same magniture, Q, but can be positive or negative. The distance between adjacent items is always the same. In which situation is the magnitude of the electric field at point P the largest?
A) Situation A
B) Situation B
C) Situation C
D) Situation D
Two point charges are separated by 20 cm and have charges of +8.0 and +16.0 μC, respectively. What is the electric field at a point midway between the two charges?
(a) 28.8 x 106 N/C
(b) 1.44 x 107 N/C
(c) 7.2 x 106 N/C
(d) zero+
Two unequal point charges are separated as shown in the figure. The electric field due to this combination of charges can be zero.
a) Only in region 1.
b) Only in region 2.
c) Only in region 3.
d) In both regions 1 and 3.
Three charges are arranged along the x-axis: +q at x = -2d; +2q at x = d; –4q at x = 2d. Which expression gives the magnitude of the electric field at the origin (x = 0)? In the expressions below, the constant 1/(4πϵ0) has been replaced with k.
A. 5kq / 4d2
B. 11kq / 4d2
C. 13kq / 4d2
D. 3kq / 4d2
Five particles are shot from the left into a region that contains a uniform electric field. The numbered lines show the paths taken by the five particles. A negatively charged particle with a charge -3Q follows path 2 while it moves through this field. Do not consider any effects due to gravity. Which path would be followed by a charge +6Q?
Path 1
Path 2
Path 3
Path 4
Path 5
In the figure, point A is a distance L away from a point charge Q. Point B is a distance 4L away from Q. What is the ratio of the electric field at B to that at A, EB/EA?
A) 1/16
B) 1/9
C) 1/4
D) 1/3
E) This cannot be determined since neither the value of Q nor the length L is specified.