Physics - Electricity pt 2

The ratio of the potential difference across a metallic conductor to the current in the conductor is known as A) resistance. B) None of the above choices are correct. C) electromagnetic force. D) potential drop. E) conductivity.

A) resistance.

On some early automobiles both headlights went out when one bulb burned out. The headlights must have been connected in A) series. B) perpendicular. C) haste. D) parallel.

A) series.

The primary source of electrons in an ordinary electrical circuit is A) the electrical circuit itself. B) the back emf of motors. C) the power station generator. D) none of these E) a dry cell, wet cell or battery.

A) the electrical circuit itself.

Alternating current is normally produced by a A) generator. B) neither of these C) both of these D) battery.

A) generator.

The number of current paths in a series circuit is: A) one B) two C) three D) four

A) one

A short piece of metal that melts when a large current passes through it is a: A) surge suppressor B) circuit breaker C) relay D) fuse

D) fuse

Which statement is correct? A) Charge flows in a closed circuit. B) Voltage flows through an open or a closed circuit. C) Resistance flows though an open circuit. D) Current is the primary cause of voltage.

A) Charge flows in a closed circuit.

Three resistors with values of R, R, and R are connected in series. What is an expression for the total resistance, R, of the three resistors? A) R_eq = R_1 + R_2 + R_3 B) R_eq = R_1 = R_2 = R_3 C) R_eq = (1/R_1 + 1/R_2 + 1/R_3)^-1 D) R_eq = (1/R_1 + 1/R_2 + 1/R_3)

A) R_eq = R_1 + R_2 + R_3

Which of the following wires would have the least resistance, assuming that all of the wires have the same cross-sectional area? A) a copper wire 5 cm in length B) an iron wire 10 cm in length C) a copper wire 10 cm in length D) an iron wire 5 cm in length

A) a copper wire 5 cm in length

Which of the following circuits can be used to test whether or not a wire of a laminated heating element is cut internally? A) B) C) D) (See Angel For Circuits)

B)

Three identical resistors are connected in series to a battery. If the current of 12 A flows from the battery, how much current flows through any one of the resistors? A) 4 A B) 12 A C) 36 A D) zero

B) 12 A

In the circuit shown below, which bulb, when burned out, will cause all other bulbs to stop glowing? A) B B) A Feedback: Correct! C) F D) C (See Angel for Circuit)

B) A

A circuit has a continuous path through which charge can flow from a voltage source to a device that uses electrical energy. What is the name of this type of circuit? A) a short circuit B) a closed circuit C) a circuit schematic D) an open circuit

B) a closed circuit

Electrons are made to flow in a wire when there is A) one end of the wire is at a higher altitude than the other B) a potential difference across its ends. C) an imbalance of charges in the wire. D) more potential energy at one end of the wire than the other.

B) a potential difference across its ends.

The source of electrons lighting an incandescent ac light bulb is A) the power company. B) atoms in the light bulb filament. C) electrical outlet. D) the source voltage. E) the wire leading to the lamp.

B) atoms in the light bulb filament.

When we say an appliance "uses up electricity," we really are saying that A) electric charges are dissipated. B) electron kinetic energy is changed into heat. C) current disappears. D) electrons are taken out of the circuit and put somewhere else. E) the main power supply voltage is lowered.

B) electron kinetic energy is changed into heat.

As more resistors are added in parallel to a constant voltage source, the power supplied by the source A) decreases. B) increases. C) increases for a time and then starts to decrease. D) does not change.

B) increases.

Stretch a copper wire so that it is thinner and the resistance between its ends A) remains unchanged. B) increases. C) decreases. D) approaches infinity

B) increases.

In an electric circuit, the safety fuse is connected to the circuit in A) parallel. B) series. C) a counter-clockwise direction D) either series or parallel.

B) series.

Which set of information will allow you to calculate the kilowatt•hr usage? A) the resistance, the current, and the time the circuit operates B) the current and the time the circuit operates C) the voltage and the resistance of the circuit D) the voltage and current in the circuit

B) the current and the time the circuit operates

When resistors are connected in series, A) the same power is dissipated in each one. B) the current flowing in each is the same. C) More than one of the given answers is true. D) the potential difference across each is the same.

B) the current flowing in each is the same.

When resistors are connected in parallel, we can be certain that A) the same current flows in each one. B) the potential difference across each is the same. C) their equivalent resistance is greater than the resistance of any one of the individual resistances. D) the power dissipated in each is the same.

B) the potential difference across each is the same.

Heat a copper wire and its electric resistance A) decreases. B) remains unchanged. C) flows towards the heat source D) increases.

D) increases.

Three resistors connected in parallel carry currents labeled I, I, and I. What is an expression for the total current I in the combined system? A) I_t = I_1 + I_2 + I_3 B) I_t = I_1 = I_2 = I_3 C) I_t = (1/I_1 + 1/I_2 + 1/I_3)^-1 D) It = (1/I_1 + 1/I_2 + 1/I_3)

C) I_t = (1/I_1 + 1/I_2 + 1/I_3)^-1

When two or more resistors are connected in parallel to a battery, A) the total current flowing from the battery equals the sum of the currents flowing through each resistor. B) the equivalent resistance of the combination is less than the resistance of any one of the resistors. C) all of the given answers D) the voltage across each resistor is the same.

C) all of the given answers

In a series circuit, each circuit element has the same: A) capacitance B) resistance C) current D) voltage

C) current

If a resistor is added to a parallel circuit, the equivalent resistance: A) increases B) becomes zero C) decreases D) remains the same

C) decreases

If a resistor is added to a series circuit, the equivalent resistance: A) becomes zero B) remains the same C) increases D) decreases

C) increases

Three identical resistors are connected in parallel to a battery. If the current of 12 A flows from the battery, how much current flows through any one of the resistors? A) zero B) 36 A C) 12 A D) 4 A

D) 4 A

Three identical resistors are connected in series to a 12-V battery. What is the voltage across any one of the resistors? A) 12 V B) 36 V C) zero D) 4 V

D) 4 V

Which of the following does not affect a material's resistance? A) the temperature of the material B) the length of the material C) the type of material D) Ohm's law

D) Ohm's law

You obtain a 100-W light bulb and a 50-W light bulb. Instead of connecting them in the normal way, you devise a circuit that places them in series across normal household voltage. Which statement is correct? A) Both bulbs glow at the same reduced brightness. B) Both bulbs glow at the same increased brightness. C) The 100-W bulb glows brighter than the 50-W bulb. D) The 50-W bulb glows more brightly than the 100-W bulb.

D) The 50-W bulb glows more brightly than the 100-W bulb.

When two or more resistors are connected in series to a battery A) the equivalent resistance of the combination is equal to the sum of the resistances of each resistor. B) the same current flows through each resistor. C) the total voltage across the combination is the algebraic sum of the voltages across the individual resistors. D) all of the given answers

D) all of the given answers

Electrons move in an electrical circuit A) none of these B) by colliding with molecules. C) because the wires are so thin. D) by interacting with an established electric field. E) by being bumped by other electrons.

D) by interacting with an established electric field.

An automatic switch that opens when the current reaches a set value is called: A) fuse B) surge suppressor C) relay D) circuit breaker

D) circuit breaker

As more resistors are added in series to a constant voltage source, the power supplied by the source A) increases. B) does not change. C) increases for a time and then starts to decrease. D) decreases.

D) decreases.

A circuit is powered with a battery. Charge flows A) out of the battery and into the circuit. B) none of these C) only after a couple seconds pass. D) through both the battery and the rest of the circuit. E) from the negative battery terminal to the positive terminal.

D) through both the battery and the rest of the circuit.

The lamps in a string of Christmas tree lights are connected in parallel. What happens if one lamp burns out? (Assume negligible resistance in the wires leading to the lamps.) A) The other lamps get brighter, but some get brighter than others. B) The other lamps get dimmer, but some get dimmer than others. C) The other lamps get brighter equally. D) The other lamps get dimmer equally. E) The brightness of the lamps will not change appreciably.

E) The brightness of the lamps will not change appreciably.

In an ac circuit, the electric field A) none of these B) increases via the inverse square law. C) is non-existent. D) is everywhere the same. E) changes magnitude and direction with time.

E) changes magnitude and direction with time.

An ampere is a unit of electrical A) none of these B) all of these C) pressure. D) resistance. E) current.

E) current.

A circuit breaker often serves the same purpose as a A) battery B) None of the above choices are correct. C) All of the above choices are correct. D) capacitor. E) fuse.

E) fuse.

The number of electrons delivered daily to an average American home by an average power utility in the mid 1980s was A) none of these B) 110. C) billions of billions. D) 220. E) zero.

E) zero.