Deck 20: Mechanical Motion From Electrical Energy

Question 1

All four coils of a drum-wound armature, receiving current from a power source ____, contribute their torque to aid rotation of the armature.

A)one at a time
B)in short bursts
C)two at a time
D)simultaneously

Answer 1

D

Question 2

In a practical DC motor, the brushes are arranged so that they will short-circuit the loop as it passes through the neutral plane, which will eliminate undesirable sparking between the brushes and the ____.

A)loop
B)commutator
C)coil
D)poles

Answer 2

B

Question 3

When a(n) ____ is in the neutral plane, no torque is produced.

A)armature
B)magnet
C)coil
D)loop

Answer 3

D

Question 4

Torque of a motor can be found with a revolutions counter and stopwatch, or a tachometer, or a calibrated stroboscopic light.

Question 5

A(n) ____, a device resembling an electric motor, utilizes the interaction of magnetic forces to yield readings of torque when coupled to the shaft of a motor.

A)electrometer
B)dynamometer
C)electrodynamometer
D)magnetometer

Question 6

A single-____ armature is impractical and has a variety of faults, one of which is the irregularity of the torque that it produces.

A)loop
B)drum
C)coil
D)magnet

Question 7

The torque delivered by a motor is a less useful quantity than the single force pushing against the two vertical sides of the coil.

Question 8

Horsepower is proportional to torque and speed.

Question 9

Experimentally, the torque of a motor is measured directly by a device called a ____.

A)Prony clutch
B)torque brake
C)torque pedal
D)Prony brake

Question 10

To differentiate between torque and work, it is customary to call the unit of torque the foot-pound and the unit of work the pound-foot.

Question 11

Torque, also known as a ____, is a measure of the twisting effect that produces rotation about an axis.

A)point of return
B)point of force
C)moment of force
D)moment of return

Question 12

Horsepower equals .

Question 13

Torque is an essential component used in the calculation of the horsepower rating of a machine.

Question 14

Torque is the product of the effective length (l) of the torque arm in feet times the net force (F) on the scale in pounds.

Question 15

____ can read the rotational speed of a motor directly in revolutions per minute (rpm).

A)Tachometers
B)Speedometers
C)Electrodynamometers
D)Prony brakes

Question 16

The torque of an electric motor is caused by the interaction of two magnetic fields, namely the main magnetic field and the magnetism created by the current flowing through the ____.

A)coil
B)armature
C)loop
D)field

Question 17

A function of a commutator is to carry a current from the supply line, via the brushes, into the rotating armature.

Question 18

A steadier torque is achieved by using several coils of a ____ armature.

A)drum-wound
B)field-wound
C)brush-wound
D)wire-wound

Question 19

The left-hand rule is used with generators, and the right-hand rule applies to motors.

Question 20

A one-loop armature produces regular torque.