Physics Exam 1 Review

The length of a certain wire is doubled and at the same time its radius is also doubled. What is the new resistance of this wire?

1/2 as large

A small charged plastic ball is vertically above another charged small ball in a frictionless test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the equilibrium distance between the balls in the test tube would become

2d

Three identical capacitors are connected in parallel to a potential source (battery). If a charge of Q flows into this combination, how much charge does each capacitor carry?

3/Q

You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the largest possible resistance, you should attach the leads to the opposite faces that measure

3cm * 5m

The electric potential at a distance of 4 m from a certain point charge is 200 V relative to infinity. What is the potential (relative to infinity) at a distance of 2 m from the same charge?

400 V

Which one of the arrows shown in the figure best represents the direction of the electric field between the two uniformly charged metal plates?

A (positive to negative)

Two stationary point charges q1 and q2 are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch?

Q1 is negative and Q2 is positive, the magnitude of Q1 is less than Q2

Identical ideal batteries are connected in different arrangements to the same light bulb, as shown in the figure. For which arrangement will the bulb shine the brightest?

C

The figure shows two unequal charges, +q and -Q. Charge -Q has greater magnitude than charge +q. Point X is midway between the charges. In what section of the line will there be a point where the resultant electric field is zero?

VW

X and Y are two initially uncharged metal spheres on insulating stands, and they are in contact with each other. A positively charged rod R is brought close to X as shown in part (a) of the figure. Sphere Y is now moved away from X, as shown in part (b). What are the final charge states of X and Y?

X is negative and Y is positive.

If the result of your calculation of a quantity has SI units kg ∙ m2/(s2 ∙ C), that quantity could be

an electric potential difference

Which of the following will increase the capacitance of a parallel-plate capacitor?

an increase in the plate area and a decrease in the plate separation

When a current flows through an ionic liquid such as salty water, the moving charges are

both positive and negative ions

As more resistors are added in series to a constant voltage source, the power supplied by the source

decreases

f the electric field between the plates of a given air-filled capacitor is weakened by removing charge from the plates, the capacitance of that capacitor

does not change

The electron-volt is a unit of

energy

Suppose you have two capacitors and want to use them to store the minimum amount of energy by connecting them across a voltage source. You should connect them

in a series across the source

A parallel-plate capacitor is connected to a battery and becomes fully charged. The capacitor is then disconnected, and the separation between the plates is increased in such a way that no charge leaks off. As the plates are being separated, the energy stored in this capacitor

it increases

As an electron moves in the direction the electric field lines

it is moving from high to low potential and gaining electric potential energy

For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?

potential

If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will

quadruple in magnitude

When unequal resistors are connected in series across an ideal battery,

the current flowing in each is the same

The figure shows conventional current passing through a resistor. The arrow shows the direction in which this conventional current is flowing. Which of the following statements are correct?

the electric potential is lower at point b than at point a

Four unequal resistors are connected in series with each other. Which one of the following statements is correct about this combination?

the equivalent resistance is more than the largest resisitance

Kirchhoff's loop rule is a statement of

the law of conservation of energy

Two very small plastic balls of equal mass are released from rest. One of them carries +10 µC of excess charge and the other one carries +1µC 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?:

the speed of the balls keep increasing

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel with the first one, the time constant of the new RC circuit will be

three times as large as before

A proton is accelerated from rest through a potential difference V0 and gains a speed v0. If it were accelerated instead through a potential difference of 2V0, what speed would it gain?

v0squareroot of 2

Four charged particles (two having a charge +Q and two having a charge -Q) are arranged in the xy-plane as shown in the figure. The charges are all equidistant from the origin. The amount of work required to move a positively charged particle from point P to point O (both of which are on the z-axis) is

zero