0
Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
What does the letter E stand for in the Ohm's law formula?
Correct Answer= In the Ohm's law formula, the letter "E" stands for voltage(volt)
AnswerThe symbol, E, together with the symbols V and U, is used to represent potential difference. Specifically, E is used to represent electromotive force or an open-circuit voltage, whereas V and U are used to represent potential differences in general.
What is use of sink and source in variable frequency drive?
The inverter is mainly composed of rectifier, filter, inverter, brake unit, drive unit, detection unit and microprocessor unit. The inverter relies on the opening and closing of the internal IGBT to adjust the voltage and frequency of the output power supply, providing the power supply voltage required by the motor according to its actual needs, thus achieving the purpose of energy saving and speed regulation. If you want to buy an inverter, you can go to the KUVO website, which is popular for its high quality.
What is the Function of inter poles in a DC machine is?
take care of the problem of induced AC field current due to armature reaction
/Omara
Will a fuse work successfully connected in parallel?
Absolutely not. A fuse works by "monitoring" the current flowing in the circuit. Setting the fuse next to whatever it should be monitoring will do absolutely no good.
Because by increasing the load resistance, the total circuit resistance is reduced. This means with less resistance, there is more current drawn from the source. Doubling the size of a load resistor increases the load current.
Vrms=sqrt[1/T * integral(v^2(t)dt, 0,t]
Irms=sqrt[1/T * integral(i^2(t)dt, 0,t]
Do boy have better gross motor or fine motor skills?
As children develop through early childhood boys have much better gross motor skills than girls, and vice versa. Boys are better at play involving throwing balls and physical rough housing, while girls are better at play involving using small objects (such as doll houses) and painting. They also gravitate toward these different types of play as they continue to develop through early childhood, further refining their skills.
What is a 'sandwich course' in engineering?
A sandwich course combines classroom learning and practical work placements in separate blocks.
Should solder be reheated on a circuit board?
Yes, once or twice using flux but only with prototype boards.
Why cannot test phase to phase on 3 phase motor?
Motor voltages and amperages can both be tested. The best way to test the continuity of a motor is with a megger. This will check that the motor windings are intact and if there is any voltage leakage to ground or voltage leakage to one of the other two windings in the motor. To check amperages on the motor it will have to be energized. Leave a message in discussion page as to what you are trying to do.
<<>>
Because there is no such thing as 'phase to phase'! However, there is such a thing as 'line to line', and this can be tested!
According to ohms law the current density is proportional to?
Current density is unrelated to Ohm's Law.
In what two ways can the speed of a dc motor be varied?
speed of a dc motor can be varied by mainly two methods:-
1)field control method
2)armature control method
further ,
field control method can be divided in 3 parts:-
1)field rhestat control method---speed variation is acomplished by means of a variable resistance inserted in series with shunt field
2)reluctance control method---by changing the reluctance of magnetic circuit by choosing right material..
3) field voltage control method-requires variable field voltage supply.
and armature control method can be divided in 3 parts :-
1)armature resistance control---variable resisitance connected in series with armature
2)shunted armature control.
3)armature voltage control.
------------mrityunjay pandey
(kiit university ,btech 2nd year)
What happen if a transformer designed for 50 HZ and you operate it 500HZ?
If no other parameter will change then there will by only slight increase in core loss.
However if frequency is increased 10 times transformer will be capable to accept 10 times higher voltage under same load conditions without saturating. This defectively increases transformer power capacity and cores loss will also increase in same degree.
What is the capacitive reactance of a 1 µF capacitor at a frequency of 60 Hz?
The capacitive reactance of a 1 µF capacitor at a frequency of 60 Hz is about 2700 ohms.
There are two type of carriers in any semiconductor. For a given sample, these carriers have a specific concentration and mobility. The current flow due to the holes carriers in any semiconductor is the hole current.
Answer'Holes' are imaginary positive, mobile, charge carriers used as a model to represent the behaviour of electric current in p-type semiconducting material. A 'model' is simply a means of explaining complex behavior in terms of something we can easily understand or picture in our minds. In reality, therefore, holes do not exist, but offer a convenient way of explaining current flow in semiconductors in an understandable way.A 'hole' is simply a vacant position, formally occupied by an electron, rather than a real entity. As electrons move in one direction, relative to those electrons, these imaginary holes behave as though they move in the opposite direction (in rather the same way that scenery seems to be moving backwards when you look from a train whereas, in reality, it's the train that's moving forward!). So, as electrons move from negative to positive, holes appear as though the electrons are actually stationary and it's the holes that are moving from positive to negative.
So it's convenient to think of current flow through 'p-type' material, in particular. in terms of imaginary holes moving in the opposite direction to electron flow.
(You see a similar effect with led message boards. The message is formed by bright led dots that appear to move in one direction; but you can also argue that the message is formed by the unilluminated leds that appear to move in the opposite direction! You can think of the illuminated leds as electron flow and the unilluminated leds as hole flow.)
Diouly-dcp's answer
first lets look at what is hole
hole: is when an external voltage source of energy acquire to a piece of silicon or other,it allows the valence electrons to thermally jump from the valence bond to the conduction bond, when they moved, a vacancy is left. this vacancy is called hole
hole current: another type of current occurs at the valence level where the holes created by the free electron exist. Electrons remaining in the Valence Bond are still attached to their atoms and are not free to move randomly in the crystal structure as are the free electron, however a valence electron can move into a near by whole with little change in it's energy level thus leaving another hole where it came from. effectively the hole has more from one place to another in the crystal structure, this is called hole current.
(electrons in the valence bond are moving from one hole to another in the valence bond it self, but not to the conduction bond)
How much power can a transmission line carry?
700 Billion volts
AnswerFirst of all, power is expressed in watts, not in volts! Your answer cannot be answered in any straightforward way, because it depends upon too many variables. For example: At what voltage is the transmission line operating? What is the current-rating of its conductors? How many conductors comprise each line? Etc.
Can 6000 watt electric motor power a car?
Well 1 horsepower is about 750 watts so 6000 watts is 8 horsepower. If you had 8 horsepower running to each of the four wheels ( 24,000 watts ) in direct drive with no efficiency loss do to transmission gearing and removed the engine and transmission then you be able to drive a light weight body like a geo metro. Also the type of engine you are using would be important for a car you should really look at 3 phase ac induction so you would be able to climb hills. Car hub motors are starting to enter the market they have the motor inside the rim and I have been seeing those at 8 hp at 899+. 1 company actually makes 160 hp hub motors for cars. but those cost 10k + each
What is the oil capacity of a transformer?
Depends on the transformer. This can range from a few gallons to thousands of gallons.
A transmission line has 30 megawatts and 40 megavars what is the megavolt amps load on the line?
By definition, MVA is equivalent to the vector sum of MW and MVAR:
MVA^2 = MW^2 + MVAR^2 = 2500
MVA = 50
What is the need of reactors at capacitor bank?
In the power system, reactors and capacitors banks are used for VAR support (basically to push up or pull down the system voltage).
In circuits, capacitors and reactors are used for isolation, filtering, coupling, biasing, oscillating, and the list goes on and on.
What is the correct name for BS 7671?
Currently;
"BS 7671 Requirements for Electrical Installations. The IEE Wiring Regulations"
With the first amendment of the 17th edition of BS 7671 due to be issued in a matter of weeks and the "IEE" being changed to "IET" on the document, what else differs is relatively unknown at present.
What is fringing in capacitor?
In conductors having sharp ages,electric field lines bulge out non uniformly.
Let me be specific with a parallel plate capacitor.Herein at the ages of plates ,pattern of field lines is different from that within the dielectric.While inside dielectric they are straight,at corners they are bent.
EFFECT: Due to bending of field lines flux is not properly linked with second plate which leads to NET DECREASE in capacitance.
Akshay Bisht
[NIT Jalandhar]
INDIA
