Electromagnetism TEST

Who invented the first battery?

 

Volta

 

Lenz

 

Faraday

 

Oersted

Volta

What law states that the induced current flows in a direction such that is opposes the action that induces it?

 

Faraday

 

Lenz

 

Volta

 

Oersted

Lenz

Which of the following states that an electric current will flow in the conductor if it cuts, or is cut by, a changing magnetic field?

 

Volta's Law

 

Lenz's Law

 

Faraday's Law

 

Oersted's Law

Faraday's Law

What does the right thumb rule indicate?

 

direction of the magnetic field around a wire without a current

 

direction the wire will rotate in a magnetic field

 

direction of the current in a wire

 

direction of magnetic field lines around a current carrying wire

direction of magnetic field lines around a current carrying wire

What is a coil of wire with a current wrapped around an iron core called?

 

solenoid

 

motor

 

electromagnet

 

generator

electromagnet

What is the power loss in a transformer that is due to the swirling of current?

 

copper losses

 

hysteresis

 

eddy currents

 

impedance

eddy currents

In America, the standard current produced is strictly maintained at                  cycles per second.

 

50

 

30

 

60

 

120

60

As the number of turns (loops) in a generator decreases, the current will                       .

 

increase

 

decrease

 

not change

decrease

In a generator, as the magnetic field strength decreases, the current will                 .

 

increase

 

decrease

 

not change

decrease

As the speed of the wire                    across the magnetic field in a generator, the amount of current will                   .

 

increase/increase

 

increase/decrease

 

decrease/increase

 

decrease/stays the same

 

increase/increase

In a generator, as wire cuts through a magnetic field, which direction will give the least amount of current?

 

45 degree angle

 

0 degree

 

90 degree angle

0 degree

Which of the following types of transformer construction is most commonly used in modern x-ray generating equipment?

 

air core

 

closed core

 

open core

 

shell type

shell type

Which of the following describes the principle by which an autotransformer is able to accomplish voltage regulation?

 

hysteresis

 

self induction

 

mutual induction

 

chocke coil

self induction

What is the power loss in a transformer that is due to the reversing magnetic domains termed?

 

copper losses

 

eddy currents

 

impedance

 

hysteresis

hysteresis

Which of the following describes a voltage regulating device which is constructed to permit only a fixed ratio of input to output voltage?

 

variable resistor

 

step up transformer

 

autotransformer

 

variable transformer

 

step up transformer

A transformer has 200 turns in a the primary circuit and the secondary contains 120,00 turns. The applied voltage is 150 volts at 10 amperes. What is the output (secondary) voltage?

 

.25 V

 

90,000 V

 

6,000 V

 

70,000 V

90,000 V

A given transformer contains 10,000 turns of wire in the primary core and 400 secondary turns. If the input (primary) is 12 amperes, what is the output (secondary) amperage? 

 

300 amps

 

.48 amps

 

2.0 amps

 

4,800 amps

300 amps

What type of current is required for a step up or step down transformer to work?

 

AC

 

Pulsating DC

 

DC

AC

What principle describes the operation of a step up transformer?

 

mutual induction

 

self induction

 

magnetism

 

electrostatics

mutual induction

How can eddy currents be reduced in a transformer?

 

oil

 

isolation

 

duplication

 

lamination

lamination

Which of the following types of transformers is subject to an appreciable waste of power due to loss of magnetic flux?

 

closed core

 

shell core

 

open core

open core

What term describes a coil of wire with a current?

 

solenoid

 

helix

 

electromagnet

solenoid

What device converts electrical energy to mechanical energy?

 

electromagnet

 

motor

 

generator

 

transformer

motor

What type of transformer construction consists of only 2 wires?

 

air

 

open

 

closed

 

shell

air

What is the result of no motion of the magnet or wire when trying to induce a current?

 

mutual induction

 

alternating current

 

pulsating direct current

 

no current is induced

no current is induced

What is another reference to self induction?

 

Farady's law

 

Oersted's law

 

Lenz's law

 

step up transformer

Lenz's law

A transformer has 90 turns in the primary circuit and the secondary contains 180 turns. The applied (primary) voltage is 50 volts at 6 amperes. What is the output (secondary) amperage?

 

100

 

12

 

3

 

2.5

3

What unit expresses electromotive force of potential difference?

 

ergs

 

coulombs

 

volts

 

amperage

volts

Which of the following convers mechanical energy to electrical energy?

 

generator

 

step down transformer

 

autotransformer

 

motor

generator

Which of the following powers the rotating anode of an x-ray tube?

 

electric generator

 

synchronous motor

 

induction motor

 

DC generator

induction motor