AP Phys 2 Circuits MCQ

Students conducting an experiment to determine the internal resistance r of a battery construct the circuit shown above... which of the following best represents the expected graph of the data?

Linear decreasing

Two students want to determine whether a lightbulb is ohmic... which of the following lists the possible quantities to graph and correctly justifies why the quantities will be useful?

The potential difference across the lightbulb as a function of the current through it, because ohmic materials obey the relationship delta V= IR

A student must determine the internal resistance of a battery... what evidence from the graph indicates that the resistors were added in parallel and not in series?

The potential difference is decreasing, not increasing.

A student is given various resistors and capacitors and is asked to design a procedure to determine the internal resistance of a battery... which of the following is the best procedure to determine the battery's resistance?

Use a resistor and measure the potential difference across and current through the resistor

A student has various metal rods of known dimensions and wants to determine whether the rods are made of the same metal by determining their resistivities... will the measurements allow the student to determine whether the rods have the same resistivity, and why or why not?

Yes, because the potential difference across the rod...

A battery, a switch S, and four identical lightbulbs A,B,C, and D are arranged in a circuit as shown above. The resistance of each lighbulb is 4.0 ohms. When the switch is closed, the current through lightbulb B is 3.0 A. What is the emf of the battery?

30 V

In the circuit shown above, is 2 uC of charge moves past point B in one second and 3 uC of charge moves past point C in one second, how much charge moves past point A in one second?

5 uC

As a capacitor is being charged in an RC circuit, the current flowing through the resistor is

decreasing

For the circuit shown in Fig. 19-46, what happens when the switch S is closed?

The capacitor eventually charges up to the full battery emf at a rate determined by R and C

Cylindrical rods of various lengths and cross-sectional areas are made of different materials... can the resistivities of the rods be compared?

Yes, because the lengths and cross-sectional areas of the rods can be measured.

In the circuit above, the capacitor is initially uncharged... what is the resistance of resistor R?

(5/4) ohms

In the circuit shown above, the capacitor is initially uncharged... what is the potential difference across the 15 ohm resistor immediately after the switch is closed?

30 V

In an electric circuit, a single wire is connected to three branches that contain resistors... conservation of which of the following best explains this phenomenon?

Electric charge

The resistors in the circuit shown above have the same resistance. Which of the following relationships is true and based only on the conservation of charge?

I2= I3+I4

A battery, a switch S, and four identical lightbulbs A,B,C, and D are arranged in a circuit as shown above. Which of the following correctly ranks the current I in each lightbulb after switch S is closed?

(Ia=Ib)>(Ic=Id)

Why is an appliance cord with a three-prong plug safer than one with two prongs?

The third prong grounds the case, so the case cannot reach a high voltage

When capacitors are connected in series, the effective capacitance is ______ the smallest capacitance; when capacitors are connected in parallel, the effective capacitance is ______ the largest capacitance.

less than; greater than

In which circuits shown in Fig. 19-40 are resistors connected in series?

(a), (c)

Two identical 10-V batteries and two identical 10-ohm resistors are placed in series as shown in Fig. 19-42. If a 10-ohm lightbulb is connected with one end connected between the batteries and other end between the resistors, how much current will flow through the lightbulb?

0 A (there is no voltage difference, so no reason for current to flow)

A 10,000-ohm resistor is placed in series with a 100-ohm resistor. The current in the 10,000-ohm resistor is 10 A. If the resistors are swapped, how much current flows through the 100-ohm resistor?

10 A

A battery, a resistor, and a capacitor are wired in a circuit with a switch... what is the voltmeter reading after a long time?

10 V

Different circuits are made using the same battery and four identical resistors. In which of the following circuits is the current in each resistor the same? Select two answers.

4 all in parallel; 4 all in series

A capacitor made of two parallel plates separated by air is charged using a battery... how does the magnitude of the final charge on each plate and the energy stored in the capacitor compare to those same quantities before the capacitor plates were moved?

Charge: less; Energy stored: less

Three identical resistors are connected to a battery, as shown above. Which of the following is a correct method for determining the potential difference across the resistor with resistance R1?

Find the equivalent resistance of the parallel resistors... the potential difference across the resistor with resistance R1 is IbR1.

When you double the voltage across a certain material or device, you observe that the current increases by a factor of 3. What can you conclude?

Ohm's law is not obeyed in this case

Which of the following statements about Ohm's law is true?

Ohm's law relates the current through a wire to the voltage across the wire

When current flows through a resistor,

Neither (a) nor (b) is true

Which resistor shown in Fig. 19-43 has the greatest current going through it? Assume that all the resistors are equal.

R5

A student has a set of identical capacitors that have the same dielectric material between the plates... will this allow the student to determine the dielectric constant of the material, and why or why not?

No, because the information does not allow comparison of different capacitances.

Why might a circuit breaker open if you plug too many electrical devices into a single circuit?

The current becomes too high

Two students connect the circuit shown above... which of the measurements will allow the students to determine the resistance of the variable resistor?

The current through the battery only

Which resistors in Fig. 19-41 are connected in parallel?

R1 and R3

A student must determine whether a circuit component has resistance... what evidence from the graph indicates that the component has resistance?

The line defined by the data does not extrapolate to zero

A student is conducting an experiment to compare the resistivity of two unknown materials by using two wires, each made of one of the materials and each connected in a circuit... which of the following must be the same to be able to compare the resistivities using just the potential difference and current measurements? Select two answers.

The length of each wire; the cross-sectional area of each wire

A student has two capacitors of unknown capacitance connected in the circuit shown above... which of the following explains why measurements of the potential difference across each capacitor and the current in each of the capacitor branches is not sufficient?

The only equation for a capacitor that is applicable... charge Q on the capacitors.

The circuits shown above have the same physical arrangement, but one resistor and the capacitor have different values... which of the following correctly compares potential difference or current and gives a correct justification? Select two answers.

The potential difference across each capacitor is 6 V because they are each connected across the battery; the current through the battery in circuit X is less than that of circuit Y because the equivalent resistance of circuit X is greater

A student has two cylindrical resistors that are made of the same material... which of the following single differences in the resistors could account for the data?

The radius of resistor X is greater than the radius of resistor Y.

When a battery is connected to a lightbulb properly, current flows through the lightbulb and makes it glow. How much current flows through the battery compared with the lightbulb?

The same amount

The unit kilowatt-hour is a measure of

an amount of energy

When the switch shown in Fig. 19-45 is closed, what will happen to the voltage across resistor R4? It will

decrease

Four lightbulbs are connected in series to a battery, as shown above. The resistances of the lightbulbs and three currents are labeled. Which of the following is a correct expression of conservation of energy in the circuit? Select two answers.

e- I1R1-I2R2-I4R4=0; I2R2-I3R3=0

When a light switch is turned on, the light comes on immediately because

the electrons already in the wire are instantly "pushed" by a voltage difference

Three uncharged capacitors with capacitances of 2 uF, 3 uF, and 6 uF are placed in a circuit with a battery of potential difference 6 V... which of the following is a correct equation for potential difference around a loop of the circuit a short time after the switch is closed but before equilibrium is reached?

q6/(6 uF) + q3/(3 uF) - q2/(2uF)= 0

A student has four pieces of wire of different lengths but with the same cross-sectional area... which of the following is a correct analysis of the data?

The wires are not made of the same material because the resistance increases by 5 ohms each time the length doubles.

Nothing happens with birds land on a power line, yet we are warned not to touch a power line with a ladder. What is the difference?

There is little to no voltage drop between a bird's two feet, but there is a significant voltage drop between the top of the ladder touching the power line and the bottom of the ladder on the ground

A battery, a switch S, and four identical lightbulbs A,B,C, and D are arranged in a circuit as shown above. How does the current in lightbulb A change, if at all, when the switch is closed, and why?

It increases because the equivalent resistance of parallel lightbulbs C and D is less than the resistance of lightbulb D.

Four cylindrical wires of different sizes are made of the same material. Which of the following combinations of length and cross-sectional area of one of the wires will result in the smallest resistance?

Length: 3L; Area: 6a

A student has a collection of resistors of unknown resistance made of various materials... will measurement of just these two quantities provide sufficient information? Why or why not?

No, because even though the resistances can be determined, resistance also depends on the dimensions of the resistor.

Each of the two circuits shown above has reached a steady state. Measuring which of the following would give the emf of one of the batteries?

The potential difference across the capacitor in circuit 2.

A student connects the circuit shown above and measures the potential difference across and current in the resistor... which of the following graphs of power as a function of current gives the best prediction for what the student's data will show?

exponential increasing (1/2 of parabola increasing)

A resistor and a capacitor are used in series to control the timing in the circuit of a heart pacemaker. To design a pacemaker that can double the heart rate when the patient is exercising, which statement below is true? The capacitor

needs to discharge faster, so the resistance should be decreased

A resistor of unknown resistance is connected to a power source with variable potential difference... the slope of the best-fit line is equal to the

resistance of the resistor

If ammeters and voltmeters are not significantly alter the quantities they are measuring,

the resistance of an ammeter should be much lower, and the resistance of a voltmeter should be much higher, than those of the circuit being measured

Electrons carry energy from the battery to a lightbulb. What happens to the electrons when they reach the lightbulb?

None of the above

Where in the circuit of Fig. 18-33 is the current the largest?

(e) it is the same at all points

When the circuit shown above is connected, the capacitor is uncharged and switch S is open... what is the current through the 200 ohm resistor at that instant?

12.5 mA

Identical resistors X and Y and two batteries are connected in the circuit represented in the diagram above... what is the potential difference e across the battery on the right?

16 V

The capacitor in the circuit shown in Fig. 19-47 is charged to and initial value Q. When the switch is closed, it discharges through the resistor. It takes 2.0 seconds for the charge to drop to 1/2Q. How long does it take to drop to 1/4Q?

4.0 seconds (discharge is not linear, but exponential)

Figure 19-44 shows three identical bulbs in a circuit. What happens to the brightness of bulb A if you replace bulb B with a short circuit?

Bulb A goes out (a short circuit has no resistance, so all current will go through)

A student has four identical resistors and needs the largest possible resistance for a branch of a circuit. How should the student arrange the resistors to get the largest possible effective resistance?

Connect all the resistors in series

A student wants to determine how increasing the total resistance in a circuit affects the current through the battery in the circuit... which of the following will accomplish this? Select two answers.

Replacing resistor X with resistors of greater resistance; replacing resistor Y with resistors of greater resistance

A student connects the circuit shown above, measures the potential difference across each of the three resistors, and finds the values shown... can this information be used as evidence for the validity of the loop rule, and why or why not?

Yes, because the sum of the potential difference values for the resistors in the rightmost branch is equal to the potential difference value for the resistor in the middle, within measurement error.

A battery, a resistor, and a capacitor are wired in a circuit with a switch... for which of the following pairs of points would the voltmeter give a nonzero reading?

a and d

When the switch shown in Fig. 19-45 is closed, what will happen to the voltage across resistor R1? It will

increase

When connected to a battery, a lightbulb glows brightly. If the battery is reversed and reconnected to the bulb, the bulb will glow

with the same brightness