28 Questions
What is the term for the difference between the magnetic poles of the earth and the true north and south?
Angle of declination
What is the characteristic of ferromagnetic materials?
They are easily magnetized
What is the symbol used to represent magnetic lines of force?
Φ (phi)
What is the behavior of like poles when they interact with each other?
They repel each other
What type of material is copper classified as?
Diamagnetic
What is the primary function of the commutator in a DC motor?
To maintain the correct polarity in the armature windings
What is the effect of Counter EMF on a DC motor?
It opposes the applied EMF
What determines the amount of torque produced by a DC motor?
The strength of both the magnetic field of the pole pieces and the armature
What is the purpose of interpoles in a DC motor?
To correct armature reaction
What is the characteristic of a Series Motor?
High torque and poor speed characteristics
What is the primary mechanism by which a DC motor produces torque?
Forces of attraction and repulsion of magnetism
What is the primary factor in determining the strength of an electromagnetic field?
The number of turns of wire around the core material
What is the term for the ability of a core material to become magnetized?
Permeability
When current stops flowing, what happens to the core material?
It remains magnetized for a period of time
What is the purpose of the left-hand rule in electromagnetism?
To determine the polarity of an electromagnet
What are the three systems for measuring magnetism?
English, CGS, and MKS
What is the purpose of the Commutator in a DC generator?
To change the AC in the armature into DC
What type of armature winding is used for higher voltage lower current operations?
Wave wound
What is the term for the point at which there is 0 volts present in the commutator?
Neutral plane
What are the three main types of field windings in a DC generator?
Series, Shunt, and Compound
What is the main principle behind the operation of a DC generator?
Magnetic induction
What is the function of the Brushes in a DC generator?
To connect the armature to the outer circuit
What is the function of the shunt field relay in a DC motor?
To disconnect power to the armature if shunt field current drops below a certain value
What is the unit of power equivalent to 1 Horsepower?
746W
What is the purpose of a hall effect sensor in a brushless DC motor?
To indicate the exact position of the rotation of the armature
What is the correct way to reverse the direction of rotation of a DC motor?
By changing the 2 leads of the armature or the field, but not both
What is the characteristic of a short shunt compound motor?
The shunt field is in parallel with the armature only
What is the purpose of the right-hand rule in motors?
To determine the direction of thrust and the magnetic field and current
Test your understanding of DC Motors, including the methods to correct armature reaction and the factors that determine the amount of torque produced. Learn about the importance of magnetic fields and their role in motor operation.
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