Question 1

The primary coil of a transformer has 200 turns and its secondary coil has 40 turns. If the current in the secondary coil is 25 A, the current in the primary coil is

Accepted Answer

A)  5 A. 
B)  6.4 A. 
C)  2.5 A. 
D)  125 A. 
A)  5 A. 
B)  6.4 A. 
C)  2.5 A. 
D)  125 A. A

Question 2

The watt, the unit of power, is equal to the

Accepted Answer

A) (volt)(ampere). 
B) volt/ampere. 
C) ampere/volt. 
D) (volt)(ohm). 
A) (volt)(ampere). 
B) volt/ampere. 
C) ampere/volt. 
D) (volt)(ohm). A

Question 3

Direct electric current cannot be used to operate

Accepted Answer

A) electric motors. 
B) electric heaters. 
C) electromagnets. 
D) transformers. 
A) electric motors. 
B) electric heaters. 
C) electromagnets. 
D) transformers. D

Question 4

A kilowatt hour is a unit of

Accepted Answer

A) energy. 
B) power. 
C) potential difference. 
D) electric charge. 
A) energy. 
B) power. 
C) potential difference. 
D) electric charge.

Question 5

The volt is the unit of electric

Accepted Answer

A) current. 
B) potential difference. 
C) potential energy. 
D) resistance. 
A) current. 
B) potential difference. 
C) potential energy. 
D) resistance.

Question 6

Which of the following statements is not true?

Accepted Answer

A) The positive charge in an atomic nucleus is due to the protons it contains. 
B) All protons have the same charge. 
C) Protons and electrons have charges equal in magnitude although opposite in sign. 
D) Protons and electrons have equal masses. 
A) The positive charge in an atomic nucleus is due to the protons it contains. 
B) All protons have the same charge. 
C) Protons and electrons have charges equal in magnitude although opposite in sign. 
D) Protons and electrons have equal masses.

Question 7

A transformer used to reduce 240-V ac to 120-V ac has an input current of 15 A. Its output current is

Accepted Answer

A)  5 A. 
B)  7.5 A. 
C)  15 A. 
D)  30 A. 
A)  5 A. 
B)  7.5 A. 
C)  15 A. 
D)  30 A.

Question 8

The resistance of a 30-W, 12-V light bulb is

Accepted Answer

A) 0.21 ohms. 
B) 0.4 ohms. 
C) 2.5 ohms. 
D) 4.8 ohms. 
A) 0.21 ohms. 
B) 0.4 ohms. 
C) 2.5 ohms. 
D) 4.8 ohms.

Question 9

Three 12-V batteries cannot be connected to give a voltage for the set of

Accepted Answer

A) 6 V. 
B) 12 V. 
C) 24 V. 
D) 36 V. 
A) 6 V. 
B) 12 V. 
C) 24 V. 
D) 36 V.

Question 10

Superconductivity occurs in certain substances

Accepted Answer

A) only at very low temperatures. 
B) only at very high temperatures. 
C) at all temperatures. 
D) only when they are in the liquid state. 
A) only at very low temperatures. 
B) only at very high temperatures. 
C) at all temperatures. 
D) only when they are in the liquid state.

Question 11

Which of the following statements is not true?

Accepted Answer

A) Protons are positively charged. 
B) The proton mass is greater than the electron mass. 
C) The proton mass is almost the same as the neutron mass. 
D) A proton in an atom circulates around its nucleus. 
A) Protons are positively charged. 
B) The proton mass is greater than the electron mass. 
C) The proton mass is almost the same as the neutron mass. 
D) A proton in an atom circulates around its nucleus.

Question 12

A current-carrying wire is in a magnetic field with the direction of the current perpendicular to that of the field.

Accepted Answer

A) The wire tends to move parallel to the field. 
B) The wire tends to move perpendicular to the field. 
C) The wire tends to turn until it is perpendicular to the field. 
D) The wire has no tendency to move or to turn. 
A) The wire tends to move parallel to the field. 
B) The wire tends to move perpendicular to the field. 
C) The wire tends to turn until it is perpendicular to the field. 
D) The wire has no tendency to move or to turn.

Question 13

A molecule that has lost an electron becomes a

Accepted Answer

A) positive ion. 
B) negative ion. 
C) nucleus. 
D) superconductor. 
A) positive ion. 
B) negative ion. 
C) nucleus. 
D) superconductor.

Question 14

The power rating of an electric motor that draws a current of 3 A when operated at 240 V is

Accepted Answer

A) 80 W. 
B) 720 W. 
C) 1080 W. 
D) 2160 W. 
A) 80 W. 
B) 720 W. 
C) 1080 W. 
D) 2160 W.

Question 15

Two 60-watt light bulbs are connected in parallel across a 120-V power line. The current in each bulb is

Accepted Answer

A)  0.5 A. 
B)  1.0 A. 
C)  2.0 A. 
D)  7200 A. 
A)  0.5 A. 
B)  1.0 A. 
C)  2.0 A. 
D)  7200 A.

Question 16

A charge of +Q attracts a charge of -Q 1 cm away with a force of F. Another charge of +Q is placed next to the first one. The force on the charge of -Q is now

Accepted Answer

A)  F/2. 
B)  F. 
C)  2F. 
D)  4F. 
A)  F/2. 
B)  F. 
C)  2F. 
D)  4F.

Question 17

A current is flowing south along a power line.Neglecting the earth's field, the direction of the magnetic field under the power line is

Accepted Answer

A) north. 
B) south. 
C) east. 
D) west. 
A) north. 
B) south. 
C) east. 
D) west.

Question 18

A negative electric charge

Accepted Answer

A) interacts only with positive charges. 
B) interacts only with negative charges. 
C) interacts with both positive and negative charges. 
D) may interact with either positive or negative charges, depending on circumstances. 
A) interacts only with positive charges. 
B) interacts only with negative charges. 
C) interacts with both positive and negative charges. 
D) may interact with either positive or negative charges, depending on circumstances.

Question 19

A drawing of the field lines of a magnetic field provides information on

Accepted Answer

A) the direction of the field only. 
B) the strength of the field only. 
C) both the direction and the strength of the field. 
D) the source of the field. 
A) the direction of the field only. 
B) the strength of the field only. 
C) both the direction and the strength of the field. 
D) the source of the field.

Question 20

Two charges repel each other with a force of 10-6 N when they are 10 cm apart.When they are brought closer together until they are 2 cm apart, the force between them becomes

Accepted Answer

A) 4 * 10-8 N. 
B) 5 * 10-6 N. 
C) 8 * 10-6 N. 
D) 2.5 * 10-5 N. 
A) 4 * 10-8 N. 
B) 5 * 10-6 N. 
C) 8 * 10-6 N. 
D) 2.5 * 10-5 N.

The primary coil of a transformer has 200 turns and its secondary coil has 40 turns. If the current in the secondary coil is 25 A, the current in the primary coil is

The watt, the unit of power, is equal to the

Direct electric current cannot be used to operate

A kilowatt hour is a unit of

The volt is the unit of electric

Which of the following statements is not true?

A transformer used to reduce 240-V ac to 120-V ac has an input current of 15 A. Its output current is

The resistance of a 30-W, 12-V light bulb is

Three 12-V batteries cannot be connected to give a voltage for the set of

Superconductivity occurs in certain substances

Which of the following statements is not true?

A current-carrying wire is in a magnetic field with the direction of the current perpendicular to that of the field.

A molecule that has lost an electron becomes a

The power rating of an electric motor that draws a current of 3 A when operated at 240 V is

Two 60-watt light bulbs are connected in parallel across a 120-V power line. The current in each bulb is

A charge of +Q attracts a charge of -Q 1 cm away with a force of F. Another charge of +Q is placed next to the first one. The force on the charge of -Q is now

A current is flowing south along a power line.Neglecting the earth's field, the direction of the magnetic field under the power line is

A negative electric charge

A drawing of the field lines of a magnetic field provides information on

Two charges repel each other with a force of 10^-6 N when they are 10 cm apart.When they are brought closer together until they are 2 cm apart, the force between them becomes

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Exam 6: Electricity and Magnetism

The primary coil of a transformer has 200 turns and its secondary coil has 40 turns. If the current in the secondary coil is 25 A, the current in the primary coil is

The watt, the unit of power, is equal to the

Direct electric current cannot be used to operate

A kilowatt hour is a unit of

The volt is the unit of electric

Which of the following statements is not true?

A transformer used to reduce 240-V ac to 120-V ac has an input current of 15 A. Its output current is

The resistance of a 30-W, 12-V light bulb is

Three 12-V batteries cannot be connected to give a voltage for the set of

Superconductivity occurs in certain substances

Which of the following statements is not true?

A current-carrying wire is in a magnetic field with the direction of the current perpendicular to that of the field.

A molecule that has lost an electron becomes a

The power rating of an electric motor that draws a current of 3 A when operated at 240 V is

Two 60-watt light bulbs are connected in parallel across a 120-V power line. The current in each bulb is

A charge of +Q attracts a charge of -Q 1 cm away with a force of F. Another charge of +Q is placed next to the first one. The force on the charge of -Q is now

A current is flowing south along a power line.Neglecting the earth's field, the direction of the magnetic field under the power line is

A negative electric charge

A drawing of the field lines of a magnetic field provides information on

Two charges repel each other with a force of 10-6 N when they are 10 cm apart.When they are brought closer together until they are 2 cm apart, the force between them becomes

The Scientific Method

Motion

Energy

Energy and the Future

Matter and Heat

Waves

The Nucleus

The Atom

The Periodic Law

Crystals, Ions, and Solutions

Chemical Reactions

Organic Chemistry

Atmosphere and Hydrosphere

The Rock Cycle

The Evolving Earth

The Solar System

The Stars

The Universe

Filters

Two charges repel each other with a force of 10^-6 N when they are 10 cm apart.When they are brought closer together until they are 2 cm apart, the force between them becomes