30 Questions
What is the principle behind the operation of DC generators?
Faraday's law of electromagnetic induction
What is the hysteresis loop area a measure of?
Energy loss in a ferromagnetic material
What happens when a conductor is placed in a varying magnetic field?
An electromotive force gets induced
If a charge of 4 coulombs is passed in 1 second, what is the current?
4 Ampere
If 3 joules of work is done to charge a body to 1 coulomb, what is the voltage?
3 Volt
What is the condition for inducing an emf in a conductor according to Faraday's law of induction?
When it cuts the magnetic flux
What is the SI unit of magnetic flux?
Weber
What does EMF stand for?
Electromotive force
What is proportional to the magnitude of the induced emf in a circuit?
Rate of change of magnetic flux
If a current of 7 amperes flows for 1 second, what is the charge?
7 coulombs
What is the mathematical expression for the magnitude of induced emf?
ε = -dϕ/dt
What is the unit of frequency?
Hertz
What is the unit of electromotive force that measures the potential difference in electric potential between two points?
Volt
What is the relationship between the magnetic field strength and the magnetic flux density of a material represented by?
B-H curve
What does the negative sign in Faraday's second law of electromagnetic induction indicate?
The direction of the induced emf
What is the frequency of an alternating current?
The number of waves passing through a point in one second
What is the unit of magnetic flux density?
Tesla
What is the magnetic flux density represented by in the B-H curve?
Magnetic flux density
What is the formula to find the equivalent resistance between two nodes in a delta-connected circuit?
Rc+Rb+Rc*Rb/Ra
What is the equivalent resistance between node 1 and node 3 in the star connected circuit?
29ohm
What is the relation between line voltage and phase voltage in a delta-connected load?
Line voltage is equal to phase voltage
What generates a polyphase system?
Having two or more generator windings separated by equal electrical angle
What is the condition for a polyphase system to be generated?
The generator windings are separated by equal electrical angle
What determines the electrical angle or displacement in a polyphase system?
The number of windings or phases
What is the advantage of a three-phase AC system over a single-phase AC system?
All of the above
Why does a three-phase system need less conductor material than a single-phase system?
To transmit a specific power over a specific distance at a given rated voltage
What is the benefit of a three-phase supply system in terms of voltage drop?
Lower voltage drop
What is the characteristic of the magnetic field produced by a three-phase power supply system?
Uniform rotating magnetic field
What is the correct sequence of three-phase voltages reaching their maximum positive values?
A-B-C
What is the type of three-phase connection described in the text?
Three-Phase Three-Wire Star Connected System
Understand the principles of electromagnetic induction and Faraday's law of induction. Learn how DC generators generate electricity and the conditions required to induce an electromotive force in a conductor.
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