30 Questions
Inside a magnet, the magnetic field lines move from:
South to north
What determines the direction of rotation of a coil in an electric motor?
Fleming's right hand rule
How can current be induced in a coil?
By moving the coil in a magnetic field
What principle does a DC generator operate on?
Newton's third law of motion
According to Oersted, how are electricity and magnetism related?
Magnetism causes electricity
Which rule helps remember the direction of magnetic field, current, and magnetic thrust force when a conducting rod is introduced to a magnetic field?
Newton's second law of motion
What is the SI unit of magnetic flux?
Tesla
Which physicist is the unit of magnetic flux named after?
Wilhelm Weber
What does EMF stand for in the context of electromotive force?
Electromagnetic Flux
How is one Volt defined?
Joule/Coulomb
In the B-H curve, what does 'H' represent?
Magnetizing Force
What does the B-H curve graphically represent?
Magnetic Field Strength vs. Magnetic Flux Density
What is the equivalent resistance between nodes A and B in the star connected circuit?
32 ohm
In a delta-connected load, what is the relation between line voltage and phase voltage?
Line voltage = phase voltage
When transforming from a star to delta connection, what should be added to find the equivalent resistance?
Sum of the resistances
What does a polyphase system require for generation?
Having two or more generator windings separated by equal electrical angle
In a delta connection, what is the equivalent resistance between nodes B and C?
$R_c + R_b + R_c * R_b / R_a$
What is the relationship between line voltage and phase voltage in a delta-connected load?
$Line voltage = Phase voltage$
What is the material commonly used in electromagnets and magnetic circuits due to its high magnetic permeability?
Soft Iron
Which law suggests that the direction of induced EMF opposes the change in magnetic flux?
Lenz's Law
What corresponds to MMF in a magnetic circuit in an electric circuit?
EMF
From which material would the B-H curve not be a straight line due to high saturation magnetization?
Soft Iron
Which material has the least area of Hysteresis loop among the options?
Soft Iron
How can the direction of induced EMF be accurately determined according to electromagnetic laws?
Fleming's Right Hand Rule
In a polyphase electrical system, what does having two or more generator windings separated by equal electrical angle result in?
Generation of polyphase electrical system
What is the electrical angle between each phase in a three-phase electrical system?
120 degrees
What is the sum of all three generated voltages in a three-phase AC circuit?
Zero (0)
In a star connected three-phase AC circuit, how does the phase voltage compare to the line voltage?
Phase voltage is square root three times line voltage and phase current is equal to line current
What determines the electromotive force generated in each coil in a three-phase AC circuit?
Magnitude and direction of the coils
Why are the windings in a three-phase alternator displaced by 120 degrees from each other?
To create a balanced and efficient power generation system
Test your knowledge on Oersted's discovery of the relationship between electricity and magnetism and the direction of magnetic field lines. Determine the correct answers related to magnetic field direction inside a magnet and the rotation of a coil in an electric motor.
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