Exam 1 Flashcards
If I move q2 twice as far away, the force on q1 will be?
1/4 as big
A test charge of +3 µC is at a point P where an external
electric field is directed to the right and has a
magnitude of 4 ×106 N/C. If the test charge is replaced
with another test charge of −3 µC, what happens to
the external electric field at P?
it is unaffected
A free electron and a free proton are released in
identical electric fields. Compare the magnitudes of
their accelerations.
it is much greater for the electrons
The total electric field at a point is the ___ ____of
the fields due to all the charges present.
vector sum
equation for linear charge density
lamba=q/l = dq=lamda * dl
equation for surface charge density
σ=q/A = dq =σdA
equation for volume charge density
ρ = q/V =dq = ρdV
what components of E cancel out by symmetry of a charged ring
most importantly Y but also z
what is a dipole
a rigid body with 2 equal and opposite charges
what is the net force on a dipole
Net force on the dipole is zero in a uniform electric field
Which of the following describes the electric field inside this conductor?
it is always zero
The charge density inside the conductor is:
0
Two charged objects are separated by some distance. The charge on the first object is greater than the charge on the second object. How does the force between the two objects compare?
The charged objects exert electrostatic forces on each other that are equal in magnitude and opposite in direction.
Two charged objects separated by some distance attract each other. If the charges on both objects are doubled with no change in distance between them, what happens to the magnitude of the force between the objects?
The force between them quadruples.
Which of the following statements are true?
A:The electric force acting on a point charge is proportional to the magnitude of the point charge.
B:Electric field lines near positive point charges radiate outward.
C:In a uniform electric field, the field lines are straight, parallel, and uniformly spaced.
D:Electric field lines near negative point charges circle clockwise.
E:The electric field created by a point charge is constant throughout space.
A B C
When a point charge of +q is placed on one corner of a square, an electric field strength of 2 N/C is observed at the center of the square. Suppose three identical charges of +q are placed on the remaining three corners of the square. What is the magnitude of the net electric field at the center of the square?
The magnitude of the net electric field at the center of the square is 0 N/C.
There is a single electron at a distance from the point charge. On which of the following quantities does the force on the electron depend?
A: the distance between the positive charge and the electron B :the charge on the electron C: the mass of the electron D: the charge of the positive charge E: the mass of the positive charge F: the radius of the positive charge G: the radius of the electron
A B D
Gaussian surfaces A and B enclose the same positive point charge. The area of surface A is two times larger than that of surface B. How does the total electric flux through the two surfaces compare?
The total electric flux through the two surfaces is equal.
A positive charge moves in the direction of an electric field. Which of the following statements are true?
A: The amount of work done on the charge cannot be determined without additional information.
B: The electric field does not do any work on the charge.
C: The electric field does positive work on the charge.
D: The potential energy associated with the charge increases.
E:The potential energy associated with the charge decreases.
F: The electric field does negative work on the charge.
A C E
A positive charge is moved from point A to point B along an equipotential surface. How much work is performed or required in moving the charge?
No work is performed or required in moving the positive charge from point A to point B.
A positive charge moves in a direction opposite to that of an electric field. What happens to the energy associated with the charge?
A: The electric potential energy of the charge increases, and the kinetic energy decreases.
B: Both the electric potential energy and the kinetic energy of the charge decrease.
C: The electric potential energy of the charge decreases, and the kinetic energy increases.
D: Both the electric potential energy and the kinetic energy of the charge increase.
A
which statments are true?
A: An equipotential surface is a three-dimensional surface on which the electric potential is the same at every point.
B: When all charges are at rest, the surface of a conductor is always an equipotential surface.
C: The potential energy of a test charge increases as it moves along an equipotential surface.
D: The potential energy of a test charge decreases as it moves along an equipotential surface.
E: Electric field lines and equipotential surfaces are always mutually perpendicular.
A B E
There is a 12 V potential difference between the positive and negative ends of the jumper cables, which are a short distance apart. An electron at the negative end ready to jump to the positive end has a certain amount of potential energy. On what quantities does this electrical potential energy depend?
only the potential difference and the charge
Assume that two of the electrons at the negative terminal have attached themselves to a nearby neutral atom. There is now a negative ion with a charge −2e at this terminal. What are the electric potential and electric potential energy of the negative ion relative to the electron?
The electric potential is the same and the electric potential energy is twice as much.
