Deck 15: Electromagnetic Induction

Question 1

Relative motion between a conductor and a magnetic field will result in a __________ being induced into the conductor

A) voltage
B) current

Answer 1

voltage

Question 2

The direction of the induced __________ depends on the __________ of motion of the __________ relative to the __________

A) voltage, velocity, conductor, field
B) voltage, direction, conductor, field
C) current, velocity, conductor, field
D) current, direction, field, conductor

Answer 2

voltage, direction, conductor, field

Question 3

The above action is generically called

A) motor action'
B) generator action'

Answer 3

generator action'

Question 4

The potential difference appearing across the ends of a conductor as it passes perpendicularly through a magnetic field depends upon

A) the flux density of the field
B) the length of the conductor within the field
C) the velocity of the conductor
D) all the above

Question 5

The potential difference appearing across the ends of a conductor if as it passes through a magnetic field also depends on the __________ of the angle at which the flux lines are 'cut'

A) sine
B) cosine
C) tangent

Question 6

The direction of the potential difference appearing across the ends of a conductor as it passes through a magnetic field may be determined using

A) Fleming's Left-Hand Rule (conventional flow)
B) Fleming's Right-Hand Rule (conventional flow)

Question 7

For the above rule, the first finger represent the __________, the second finger represents the __________, and the thumb indicates the ___________

A) field, current, motion
B) voltage, motion, field
C) field, voltage, motion
D) field, motion, current

Question 8

The statement that 'any current resulting from the potential difference induced into a conductor moving through a magnetic field must act in a direction such that its own magnetic field will oppose the motion of that conductor', is known as

A) Faraday's Law
B) Maxwell's Law
C) Law of the conservation of energy
D) Lenz's Law

Question 9

If a permanent magnet is moved towards a coil that forms a closed circuit, the polarity of its resulting magnetic field will

A) oppose the movement of the magnet
B) assist the movement of the magnet
C) will have no effect on the movement of the magnet

Question 10

If a permanent magnet is moved away from a coil that forms a closed circuit, the polarity of its resulting magnetic field will

A) oppose the movement of the magnet
B) assist the movement of the magnet
C) will have no effect on the movement of the magnet

Question 11

Any change in the current flowing through a coil will induce a __________ into that coil, which will __________ the change in that current

A) current, oppose
B) current, reinforce
C) voltage, oppose
D) voltage, reinforce

Question 12

The process, described above, is termed

A) self induction
B) mutual induction
C) coefficient of coupling
D) conservation of energy

Question 13

Doubling the number of turns in a coil will __________ its inductance

A) quadruple
B) double
C) halve
D) quarter

Question 14

Doubling the cross-sectional area of a coil will __________ its inductance

A) quadruple
B) double
C) halve
D) quarter

Question 15

Doubling the length of a coil will __________ its inductance

A) quadruple
B) double
C) halve
D) quarter

Question 16

The SI unit of measurement of inductance is the

A) henry
B) weber per metre
C) farad
D) ampere turn

Question 17

The most effective way of significantly increasing the inductance of a coil is to

A) increase the number of turns
B) reduce the length of the coil
C) increase its cross-sectional area
D) insert a ferromagnetic core

Question 18

If a coil is suddenly connected to a d.c. supply, the resulting current would be limited by the __________ of that coil

A) inductance
B) resistance
C) number of turns
D) permeability

Question 19

When a coil is suddenly connected to a d.c. supply, if the initial rate of increase in current was maintained, it would reach its maximum value

A) instantaneously
B) in a period of time called a 'time constant'
C) in a period of time equivalent to five 'time constants'

Question 20

The actual time taken by the current, in the above question, to reach its maximum value will be

A) instantaneously
B) in a period of time called a 'time constant'
C) in a period of time equivalent to five 'time constants'

Question 21

If a coil of inductance 0.2 H and negligible resistance, carrying a steady d.c. current were suddenly short-circuited, using a resistance of 500 ohm, the current would reach zero in

A) 0.4 ms
B) 2 ms
C) 100 s
D) 500 s

Question 22

If a change in current in one coil induces a potential difference in a second coil through

A) inductance
B) self inductance
C) mutual inductance
D) motor action

Question 23

Two separate coils, wound around a common core, in which a changing current in one coil induces a potential difference into a second coil, is called

A) an inductor
B) a mutual inductor
C) a transformer
D) an autotransformer

Question 24

The term, 'coupled', when applied to two coils, describes

A) the degree by which magnetic flux is able to link the two coils
B) how physically close they are together
C) when they share a common core

Question 25

Any magnetic flux produced in one coil that doesn't link with a second coil sharing the same magnetic circuit is termed

A) redundant flux
B) leakage flux
C) fringing

Question 26

For an 'ideal' transformer, the voltage ratio is equal to

A) turns ratio
B) reciprocal of the turns ratio
C) current ratio

Question 27

A transformer's 'primary' winding is the

A) higher-voltage winding
B) lower-voltage winding
C) winding connected to the supply
D) wingind connected to the load

Question 28

The terms, 'choke', 'reactor', and 'ballast' are

A) alternative names for an inductor
B) alternative names for a coil
C) applications for an inductor

Question 29

When determining the total inductance, inductors in series are treated like resistors in __________, and inductors in parallel are treated like resistors in __________

A) series, parallel
B) parallel, series