Question 1

The voltage induced in self-inductions is

Accepted Answer

A) always in a direction opposing the changing voltage that produced it. 
B) likely higher than the changing voltage that causes it. 
C) both of these 
D) neither of these 
A) always in a direction opposing the changing voltage that produced it. 
B) likely higher than the changing voltage that causes it. 
C) both of these 
D) neither of these C

Question 2

A principle difference between an MHD generator and a conventional generator is that the MHD generator

Accepted Answer

A) has no moving parts. 
B) operates more efficiently at high temperatures. 
C) both of these 
D) neither of these 
A) has no moving parts. 
B) operates more efficiently at high temperatures. 
C) both of these 
D) neither of these C

Question 3

High-voltage wires in power lines are not high-current wires because the current in them is

Accepted Answer

A) not the same as the current that powers the distant load. 
B) proportional to the voltage drop from beginning to end of each line, rather low. 
C) both of these 
D) neither of these 
A) not the same as the current that powers the distant load. 
B) proportional to the voltage drop from beginning to end of each line, rather low. 
C) both of these 
D) neither of these C

Question 4

A transformer actually transforms

Accepted Answer

A) voltage. 
B) magnetic field lines. 
C) generators into motors. 
D) non-safe forms of energy to safe forms of energy. 
E) all of the above 
A) voltage. 
B) magnetic field lines. 
C) generators into motors. 
D) non-safe forms of energy to safe forms of energy. 
E) all of the above

Question 5

A step-up transformer steps up voltage by ten times. If voltage input is 120 volts, voltage output is

Accepted Answer

A) 60 V. 
B) 120 V. 
C) 1200 V. 
D) 12000 V. 
E) none of the above 
A) 60 V. 
B) 120 V. 
C) 1200 V. 
D) 12000 V. 
E) none of the above

Question 6

A certain transformer doubles input voltage. If the primary coil draws 10 A of current, then the current in the secondary coil is

Accepted Answer

A) 2 A. 
B) 5 A. 
C) 10 A. 
D) 25 A. 
E) none of the above 
A) 2 A. 
B) 5 A. 
C) 10 A. 
D) 25 A. 
E) none of the above

Question 7

Voltage can be induced in a wire by

Accepted Answer

A) moving the wire near a magnet. 
B) moving a magnet near the wire. 
C) changing the current in a nearby wire. 
D) all of the above 
E) none of the above 
A) moving the wire near a magnet. 
B) moving a magnet near the wire. 
C) changing the current in a nearby wire. 
D) all of the above 
E) none of the above

Question 8

In the field induction credited to Maxwell, wires

Accepted Answer

A) can be insulated or non-insulated. 
B) are minimized. 
C) are not needed. 
A) can be insulated or non-insulated. 
B) are minimized. 
C) are not needed.

Question 9

An efficient step-down transformer decreases

Accepted Answer

A) power. 
B) energy. 
C) both of these 
D) neither of these 
A) power. 
B) energy. 
C) both of these 
D) neither of these

Question 10

To reduce the danger of self-induction

Accepted Answer

A) simply pull the circuit plug. 
B) turn off the switch to the circuit. 
C) either of these 
D) neither of these 
A) simply pull the circuit plug. 
B) turn off the switch to the circuit. 
C) either of these 
D) neither of these

Question 11

An efficient step-up transformer boosts

Accepted Answer

A) energy. 
B) power. 
C) voltage. 
D) all of the above 
E) none of the above 
A) energy. 
B) power. 
C) voltage. 
D) all of the above 
E) none of the above

Question 12

The voltage across the input terminals of a transformer is 120 V. The primary has 25 loops and the secondary has 50 loops. The voltage the transformer delivers is

Accepted Answer

A) 30 V. 
B) 60 V. 
C) 120 V. 
D) 240 V. 
E) none of the above 
A) 30 V. 
B) 60 V. 
C) 120 V. 
D) 240 V. 
E) none of the above

Question 13

The major advantage of MHD generators over conventional generators is that MHD generators

Accepted Answer

A) do not use electromagnetic induction. 
B) do not require magnets. 
C) require no power input. 
D) all of the above 
E) none of the above 
A) do not use electromagnetic induction. 
B) do not require magnets. 
C) require no power input. 
D) all of the above 
E) none of the above

Question 14

The high voltage that is important in a power line is high voltage

Accepted Answer

A) between the parallel wires of the line. 
B) from one end of each power line to the other. 
C) both of these 
D) neither of these 
A) between the parallel wires of the line. 
B) from one end of each power line to the other. 
C) both of these 
D) neither of these

Question 15

Electromagnetism unites

Accepted Answer

A) electricity and magnetism. 
B) electric and gravitational fields. 
C) physics and biophysics. 
D) all of the above 
E) none of the above 
A) electricity and magnetism. 
B) electric and gravitational fields. 
C) physics and biophysics. 
D) all of the above 
E) none of the above

Question 16

The principle difference between a step-up and step-down transformer is

Accepted Answer

A) step-up transformers can handle more current. 
B) different geometries. 
C) different ratios of turns of wire for each. 
D) none of the above 
A) step-up transformers can handle more current. 
B) different geometries. 
C) different ratios of turns of wire for each. 
D) none of the above

Question 17

Power is transmitted at high voltages because the corresponding current in the wires is

Accepted Answer

A) also high to deliver appreciable power to distant places. 
B) low so that overheating of the wires is minimized. 
C) either of these 
D) neither of these 
A) also high to deliver appreciable power to distant places. 
B) low so that overheating of the wires is minimized. 
C) either of these 
D) neither of these

Question 18

The secondary of a transformer is the coil connected to

Accepted Answer

A) the load. 
B) the Internet. 
C) the input power line. 
D) none of the above 
A) the load. 
B) the Internet. 
C) the input power line. 
D) none of the above

Question 19

The spacing between the parallel power lines is affected by

Accepted Answer

A) current-carrying capacities of wires. 
B) electrical insulation. 
C) the wing span of birds in the vicinity. 
D) none of the above 
A) current-carrying capacities of wires. 
B) electrical insulation. 
C) the wing span of birds in the vicinity. 
D) none of the above

Question 20

When a bar magnet is thrust into a coil of copper wire, the coil tends to

Accepted Answer

A) attract the magnet as it enters. 
B) repel the magnet as it enters. 
C) both of these 
D) neither of these 
A) attract the magnet as it enters. 
B) repel the magnet as it enters. 
C) both of these 
D) neither of these

Exam 25: Electromagnetic Induction

The voltage induced in self-inductions is

A principle difference between an MHD generator and a conventional generator is that the MHD generator

High-voltage wires in power lines are not high-current wires because the current in them is

A transformer actually transforms

A step-up transformer steps up voltage by ten times. If voltage input is 120 volts, voltage output is

A certain transformer doubles input voltage. If the primary coil draws 10 A of current, then the current in the secondary coil is

Voltage can be induced in a wire by

In the field induction credited to Maxwell, wires

An efficient step-down transformer decreases

To reduce the danger of self-induction

An efficient step-up transformer boosts

The voltage across the input terminals of a transformer is 120 V. The primary has 25 loops and the secondary has 50 loops. The voltage the transformer delivers is

The major advantage of MHD generators over conventional generators is that MHD generators

The high voltage that is important in a power line is high voltage

Electromagnetism unites

The principle difference between a step-up and step-down transformer is

Power is transmitted at high voltages because the corresponding current in the wires is

The secondary of a transformer is the coil connected to

The spacing between the parallel power lines is affected by

When a bar magnet is thrust into a coil of copper wire, the coil tends to

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