Chapter 23: Electric Current
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- 1.Electrons are made to flow in a wire when there is
- A.
An imbalance of charges in the wire.
- B.
More potential energy at one end of the wire than the other.
- C.
A potential difference across its ends.
- 2.An ampere is a unit of electrical
- A.
Pressure.
- B.
Current.
- C.
Resistance.
- D.
All of these
- E.
None of these
- 3.A wire that carries an electric current
- A.
Is electrically charged.
- B.
May be electrically charged.
- C.
Is never electrically charged.
- 4.A coulomb of charge that passes through a 6-volt battery is given
- A.
6 joules.
- B.
6 amperes.
- C.
6 ohms.
- D.
6 watts.
- E.
6 newtons.
- 5.Which statement is correct?
- A.
Charge flows in a closed circuit.
- B.
Voltage flows through an open or a closed circuit.
- C.
Resistance flows through an open circuit.
- D.
Current is the primary cause of voltage.
- 6.Electrons move in an electrical circuit
- A.
By being bumped by other electrons.
- B.
By colliding with molecules.
- C.
By interacting with an established electric field.
- D.
Because the wires are so thin.
- E.
None of these
- 7.Stretch a copper wire so that it is thinner and the resistance between its ends
- A.
Decreases.
- B.
Remains unchanged.
- C.
Increases.
- 8.Heat a copper wire and its electric resistance
- A.
Decreases.
- B.
Remains unchanged.
- C.
Increases.
- 9.A wire carrying a current is normally charged
- A.
Negatively.
- B.
Positively.
- C.
Not at all.
- 10.In an ac circuit, the electric field
- A.
Increases via the inverse-square law.
- B.
Changes magnitude and direction with time.
- C.
Is the same everywhere.
- D.
Is non-existent.
- E.
None of these
- 11.The current through a 10-ohm resistor connected to a 120-V power supply is
- A.
1 A.
- B.
10 A.
- C.
12 A.
- D.
120 A.
- E.
None of these
- 12.A 10-ohm resistor has a 5-A current in it. What is the voltage across the resistor?
- A.
5 V
- B.
10 V
- C.
15 V
- D.
20 V
- E.
More than 20 V
- 13.When a 10-V battery is connected to a resistor, the current in the resistor is 2 A. What is the resistor's value?
- A.
2 ohms
- B.
5 ohms
- C.
10 ohms
- D.
20 ohms
- E.
More than 20 ohms
- 14.The primary source of electrons in an ordinary electrical circuit is
- A.
A dry cell, wet cell or battery.
- B.
The back emf of motors.
- C.
The power station generator.
- D.
The electrical circuit itself.
- E.
None of these
- 15.The source of electrons lighting an incandescent ac light bulb is
- A.
The power company.
- B.
Electrical outlet.
- C.
Atoms in the light bulb filament.
- D.
The wire leading to the lamp.
- E.
The source voltage.
- 16.A woman experiences an electrical shock. The electrons making the shock come from the
- A.
Woman's body.
- B.
Ground.
- C.
Power plant.
- D.
Hairdryer.
- E.
Electric field in the air.
- 17.In a common dc circuit, electrons move at speeds of
- A.
A fraction of a centimeter per second.
- B.
Many centimeters per second.
- C.
The speed of a sound wave.
- D.
The speed of light.
- E.
None of these
- 18.When a light switch is turned on in a dc circuit, the average speed of electrons in the lamp is
- A.
The speed of sound waves in metal.
- B.
The speed of light.
- C.
1000 cm/s.
- D.
Less than 1 cm/s.
- E.
Dependent on how quickly each electron bumps into the next electron.
- 19.Alternating current is normally produced by a
- A.
Battery.
- B.
Generator.
- C.
Both of these
- D.
Neither of these
- 20.The electric power of a lamp that carries 2 A at 120 V is
- A.
1/6 watts.
- B.
2 watts.
- C.
60 watts.
- D.
20 watts.
- E.
240 watts.
- 21.When two lamps are connected in parallel to a battery, the electrical resistance that the battery senses is
- A.
More than the resistance of either lamp.
- B.
Less than the resistance of either lamp.
- C.
None of these
- 22.When two lamps are connected in series to a battery, the electrical resistance that the battery senses is
- A.
More than the resistance of either lamp.
- B.
Less than the resistance of either lamp.
- C.
None of these
- 23.On some early automobiles both headlights went out when one bulb burned out. The headlights must have been connected in
- A.
Parallel.
- B.
Perpendicular.
- C.
Series.
- D.
Haste.
- 24.Modern automobile headlights are connected in
- A.
Parallel.
- B.
Perpendicular.
- C.
Series.
- D.
None of these
- 25.There are electrons in the filament of the ac lamp in your bedroom. When you turn on the lamp and it glows, the glowing comes from
- A.
Different electrons; the ones that flow in the circuit to your lamp.
- B.
The same electrons.
- C.
The positive charges that flow in the filament.
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