Question 1

The operation of a motor depends upon the interaction between ____ magnetic fields.&#10;A) two&#10;B) three&#10;C) four&#10;D) six

Accepted Answer

The operation of a motor depends upon the interaction between two magnetic fields: the magnetic field of the stator (stationary part of the motor) and the magnetic field of the rotor (rotating part of the motor).

Question 2

A good commutator will have a very dark brown film of oxide.

Accepted Answer

A good commutator should have a uniform, light brown or tan color, indicating proper operation and minimal wear. A very dark brown film of oxide suggests excessive wear or potential electrical issues.

Question 3

Because the armature of a DC motor is wound in much the same way as a DC generator, the current from the supply must divide and flow through three or more paths.

Accepted Answer

False

Question 4

In a brushless DC motor, a special circuit is used to perform the commutation of the applied DC.

Accepted Answer

In a brushless DC motor, electronic commutation is used to switch the power to the appropriate winding at the right time, eliminating the need for brushes and commutator.

Question 5

The starting torque of a shunt motor is about ____ times the full-load torque.&#10;A) 1.75&#10;B) 2.00&#10;C) 2.75&#10;D) 3.00

Accepted Answer

The starting torque of a shunt motor is about 2.75 times the full-load torque. This is due to the fact that the field winding of a shunt motor is connected in parallel with the armature winding, which causes the motor to have a relatively constant speed and good starting torque.

Question 6

A(n) ____ motor has a very high starting torque.&#10;A) series&#10;B) shunt&#10;C) combination&#10;D) permanent magnet

Accepted Answer

A series motor has a very high starting torque due to its design where the field winding is in series with the armature winding, resulting in a strong magnetic field and high torque at low speeds.

Question 7

____ motors are designed to be used for jobs requiring minimum torque.&#10;A) Series&#10;B) Brushless DC&#10;C) Stepping&#10;D) Permanent magnet

Accepted Answer

Stepping motors are designed for precise positioning and control rather than for high torque applications. They move in discrete steps, allowing for precise control of angular or linear position, speed, and acceleration, making them ideal for applications requiring minimal torque but high precision.

Question 8

When using the right hand rule for a motor, the thumb points in the direction of ____.&#10;A) the current&#10;B) the field&#10;C) the force&#10;D) the lines of magnetic flux

Accepted Answer

The right hand rule for a motor states that if the thumb of your right hand points in the direction of the magnetic field and your fingers curl in the direction of the current, then the direction that your palm faces represents the direction of the force experienced by the conductor. Therefore, the thumb does not point in the direction of the current (choice A) or the field (choice B), but rather the force (choice C). The lines of magnetic flux (choice D) are represented by the field itself and are not part of the right hand rule for a motor.

Question 9

What is an application of a phototransistor?&#10;A) optical encoder circuit&#10;B) voltage regulation&#10;C) Hall effect device&#10;D) voltage control

Accepted Answer

Phototransistors are commonly used in optical encoder circuits to detect the rotary motion of a disk with alternating patterns of opaque and transparent regions. The phototransistor converts light into an electrical signal that can be used to determine the position and speed of the disk.

Question 10

A(n) ____ is a type of rotating switch.&#10;A) stator&#10;B) prony brake&#10;C) armature&#10;D) commutator

Accepted Answer

A commutator is a type of rotating switch commonly used in electric motors to convert the alternating current produced by the motor into direct current.

Question 11

In some types of DC motor arrangements, a flywheel assists the motor in driving the load.

Accepted Answer

The answer of In some types of DC motor arrangements,...

Question 12

Insulation tests are a type of maintenance task that should be performed on a regular basis.

Accepted Answer

The answer of Insulation tests are a type of maintenance...

Question 13

An instrument designed to measure rotating torque is called a(n) ____ .&#10;A) rotational force meter&#10;B) torquometer&#10;C) torque wrench&#10;D) prony brake

Accepted Answer

The answer of An instrument designed to measure rotating torque...

Question 14

Stepping motors that are designed with non-permanent-magnet rotors are referred to as ____ stepping motors.&#10;A) parallel&#10;B) variable reluctance&#10;C) brushless DC&#10;D) series

Accepted Answer

The answer of Stepping motors that are designed with non-permanent-magnet...

Question 15

Which type of motor has the ability to control the rotation to less than 1 degree?&#10;A) Brushless DC motor&#10;B) Stepping motor&#10;C) Series motor&#10;D) Shunt motor

Accepted Answer

The answer of Which type of motor has the ability...

Deck 17: Dc Motors