Physics 2 Exam 1

Four point charges of equal magnitude and sign are arranged on the corners of the square of side d as shown in the figure. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square? A. a B. b c. c D. d

D. d

Two very small plastic balls of equal mass are released from rest. One of them carries +10 micro-Coulombs of excess charge and the other one carries +1 micro-Coulombs of charge. No other charges or fields are present. Which of the following statements are true about them as they move away from each other? a. The balls always have accelerations of equal magnitude. b. The acceleration of the 10 micro-Coulomb ball is 1 times that of the 10 micro-Coulomb ball. c. The acceleration of the balls keeps increasing. d. The acceleration of the 10 micro-Coulomb ball is 10 times that of the 1 micro-Coulomb ball.

a. The balls always have accelerations of equal magnitude.

A hydrogen nucleus, which has a charge of +e, is situated to the left of a carbon nucleus, which has a charge +6e. Which statement is true? a. The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is equal to the force exerted on the carbon nucleus. b. The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is greater than the force exerted on the carbon nucleus. c. The electric force experienced by the hydrogen nucleus is to the left, and the magnitude is less than the force exerted on the carbon nucleus. d. The electrical force experienced by the hydrogen nucleus is to the right, and the magnitude is equal to the force exerted on the carbon nucleus.

a. The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is equal to the force exerted on the carbon nucleus.

Several electrons are placed on a hollow conducting sphere. They a. become uniformly distributed on the sphere's outer surface. b. clump together on the sphere's outer surface. c. become uniformly distributed on the sphere's inner surface. d. clump together on the sphere's inner surface.

a. become uniformly distributed on the sphere's outer surface

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. If the separation between the plates is doubled, the potential difference between the plates will a. double b. quadruple c. be cut in half d. remain the same

a. double

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. upward b. downward c. out of the page d. into the page

a. upward

Three equal charges are at three of the corners of a square of side d. A fourth charge of equal magnitude is at the center of the square as shown in the figure. Which of the arrows shown represents the net force acting on the charge at the center of the square? a. a b. b c. c d. d

b. b

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference between the plates. If the separation between the plates is doubled, the magnitude of the charge on the plates will a. double b. be cut in half c. quadruple d. not change

b. be cut in half

A disk with a radius of R is oriented with its normal unit vector at an angle θ with respect to a uniform electric field. Which of the following would result in an increase in the electric flux through the disk? a. An increase in area. b. both (a) and (b) c. neither (a) nor (b) d. An increase in the magnitude of the electric field

b. both a and b

An equipotential surface must be a. parallel to the electric field at any point. b. perpendicular to the electric field at any point. c. randomly oriented with respect to the electric field. d. equal to the electric field at any point.

b. perpendicular to the electric field at any point

How are electric field lines and equipotential surfaces related? a. They must be parallel b. They must be perpendicular. c. They can have any orientation. d. They have no relation.

b. they must be perpendicular

The main difference between conductors and insulators is in terms of a. protons b. valence or conduction electrons c. atoms d. neutrons

b. valence or conduction electrons

When a dielectric material is introduced between the plates of a parallel plate capacitor the capacitance increases by a factor of 4. What is the dielectric constant of the material introduced between the plates? a. 0.4 b. 1.4 c. 4 d. 2

c. 4

Two objects, A and B, are rubbed together. As a result, object A acquires an excess negative charge while object B becomes positively charged. In comparison to their masses before the charging process, you can say that a. the mass of A decreased and that of B increased. b. the mass of both objects decreased. c. the mass of A increased and that of B decreased. d. the mass of both objects increased.

c. The mass of A increased and that of B decreased

A negatively charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres? a. Both spheres become negative b. The spheres do not get any charge. c. The sphere near the charged rod becomes positive and the other one becomes negative. d. The sphere near teh charged rod becomes negative and the other one becomes positive.

c. The sphere near the charged rod becomes positive and the other one becomes negative.

A conductor is placed in an electric field under electrostatic conditions. Which of the following statements is correct for this situation? a. The electric field on the surface of the conductor is perpendicular to the surface. b. The electric field is zero inside the conductor. c. all of the above d. All valence electrons go to the surface of the conductor.

c. all of the above

If the result of your calculation of a quantity has SI units kg*m2/(s2*C), that quantity could be a. an electric field strength b. a capacitance c. an electric potential difference d. an electric potential energy

c. an electric potential difference

A surface on which all points are at the same potential is referred to as a. a constant electric force surface. b. a constant electric field surface. c. an equipotential surface. d. an equivoltage surface

c. an equipotential surface

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference between the plates. If the separation between the plates is doubled, the magnitude of the electrical energy stored on the capacitor will a. double b. quadruple c. be cut in half d. be cut in fourth

c. be cut in half

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference between the plates. A slab of a dielectric material is inserted in the region between the plates so as to completely fill it. What changes would you observe? a. Only the charge in the capacitor would change. b. Only the capacitance would change. c. Both the charge in the capacitor and its capacitance would change. d. Nothing would change.

c. both the charge in the capacitor and its capacitance would change

By what method will a positively charged rod produce a negative charge on a conducting sphere that is placed on an insulating surface? a. none of these. b. by means of convection c. by means of induction d. by means of conduction

c. by means of induction

The work done in moving a positive charge against an electric field does not depend on the path chosen in moving the charge in that field. Based on the statement, what kind of force field is the electrostatic field? a. discrete b. quantized c. conservative d. nonconservative

c. conservative

The electron-volt is a unit of a. Charge b. Electric Potential c. Electric Potential Energy d. Electric Force

c. electric potential energy

If the electric potential at a point in space is zero, then the electric field at that point must be a. negative b. zero c. impossible to determine based on the information given. d. positive

c. impossible to determine based on the information given

A plastic rod is charged up by rubbing a wool cloth, and brought to an initially neutral metallic sphere that is insulated from ground. It is allowed to touch the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod a. is attracted to the sphere. b. feels no force due to the sphere. c. is repelled by the sphere.

c. is repelled by the sphere

Two charges, Q1 and Q2, are separated by a certain distance R. If the magnitudes of the charges are doubled and their separation is also doubled, then what happens to the electrical force between these two charges? a. it quadruples b. it doubles c. it remains the same d. it is halved

c. it remains the same

The charge on the proton is the same as a. the charge on the atom. b. the charge on the electron. c..the charge on the electron, but of the opposite sign. d. the charge on the neutron.

c. the charge on the electron, but of the opposite sign

A negative charge is moved from point A to point B along an equipotential surface. Which of the following statements is true for this case? a. The negative charge performs work in moving from point A to point B. b. Work is required to move the negative charge from point A to point B. c. Work is both required and performed in moving the negative charge from point A to point B. d. No work is required to move the negative charge from point A to point B.

d. No work is required to move the negative charge from point A to point B.

Two protons are released from rest, with only the electrostatic force acting. Which of the following statements must be true about them as they move apart? a. Their kinetic energy keeps increasing. b. The electric potential energy keeps decreasing. c. Their acceleration keeps decreasing. d. All of the other answers are correct.

d. all of the other answers are correct

Which of the following will increase the capacitance between the plates of a parallel plate capacitor? a. Increase the charge on the plates. b. Decrease the potential between the plates. c. Increase the potential between the plates. d. Introduce a dielectric material between the plates.

d. introduce a dielectric material between the plates