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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
How do you calculate the maximum power dissipated in diode?
The power dissipated by a diode is P = Vf x I watts, where Vf is the forward voltage drop on diode (typically 0.5 volts for silicon diode) and I is the current.
What is power factor in an electrical power system?
In an alternating current system, the voltage and current may or may not rise and fall at the same time. In resistive circuits it does but the current in other cases may lead or lag the voltage.
For a single phase system
Power = Power Factor * V * I
The power factor is the cosine of the angle between V and I and is a maximum (1) in resistive circuits.
Why voltmeter should have a very high resistance?
well a voltmeter measures AC and DC voltage. resistance is a term used only for DC voltage, A voltmeter uses a term called Impedance for AC, without it, when you measure across two terminals it would create a short circuit and would blow up the meter. it is basically a safety feature to prevent people from creating short circuits when measuring.
Transformer step-up/step-down voltage is turns-ratio, so if a transformer has 20 primary windings and 100 secondary windings (a turns-ratio of 1 to 5) and the secondary voltage is 25, then is the primary voltage is 5.
What does an electrical choke do?
A choke is an inductor. The impedance of an inductor is dependent on the frequency of the current flowing through it. The greater the frequency, the higher the impedance.
Therefore an inductor when used as a choke blocks the flow of high frequency current (by presenting a high impedance), while allowing low frequency or direct current to flow through it.
Its function is to block ("choke") high frequencies while passing low frequencies.
Is the current always the same in parallel circuits?
An example of a parallel circuit would be the light bulbs in track lighting. Each bulb has the same voltage applied. The current through any one light bulb equals the voltage divided by the resistance of the bulb. The current also equals the wattage of the bulb divided by the voltage. So if all the bulbs had exactly the same resistance the current would be the same. However, your question says "always" so in general the answer is no. In the case of track lighting if you had a 60 watt bulb in parallel with a 120 watt bulb, the 60W bulb would draw 1/2 amp and the 120W bulb would draw 1 amp. The sum of the current flowing in a parallel circuit equals the sum of the current in each leg of the circuit.
when A resistance is connected across the supply voltage, total input vooltage will be drop in the resistance when the resistances are connected across the supply voltage, total input vooltage will be devidedacross the resistances. IF R value will be high ,drop also high. IF R value wll be low ,voltage drop will be less.
What is mean by busbar in electrical engineering?
it is an infinite current carrying conductor which doesn't have voltage drop.
When the conversion of a system, process, etc. Is completed in phases rather than a complete transformation at one time.
What happens to the power output of the source if more lamps are connected in parallel?
Nothing will happen to the possible output power of the power source i.e it will not increase. Each power source has its maximum possible output power. Adding more lamps in parallel will result in a drop in the circuit's total resistance which causes the total current drawn by the lamps to increase. Your wires might be burnt as a result so be careful.
What is the value of internal impedance of ideal current source?
internal resistance is always infinite in ideal current source .the internal resistance is in shunt with current source
What is the amp rating of 100va transformer?
The amp rating for a 100VA transformer will vary depending on the actual voltage of the transformer. Transformers have both a primary and a secondary voltage.
What is the use of choke in the fluorescent tube?
The inductance primarily serves to limit current flow to the correct level for the tube. It also can be used during startup to provide an inductive 'kick' forming a higher-voltage pulse to start the lamp.
How do you make a non-polarized electrolytic capacitor?
Take two electrolytic capacitors of the same voltage and capacity, connect the positive leads together and connect the negative leads to the circuit. Just keep in mind that this will reduce the cap. value by half (2, 1000uF caps = 500uF) Also the voltage of the circuit should not exceed the voltage of one of the caps.
Why must voltmeter be connected in parallel with the circuit component?
Because, by definition, a voltage is the difference in potential between two different points. So the voltmeter must be connected across those points in order to measure that voltage -i.e. in parallel with the points.B
What are the advantages of active filters over passive filters?
Active filters have three main advantages over passive filters:
- Inductors can be avoided. Passive filters without inductors cannot obtain a high Q (low damping), but with them are often large and expensive (at low frequencies), may have significant internal resistance, and may pick up surrounding electromagnetic signals.
- The shape of the response, the Q (Quality factor), and the tuned frequency can often be set easily by varying resistors, in some filters one parameter can be adjusted without affecting the others. Variable inductances for low frequency filters are not practical.
- The amplifier powering the filter can be used to buffer the filter from the electronic components it drives or is fed from, variations in which could otherwise significantly affect the shape of the frequency response.
Are the circuits at homes connected in series or parallel and why?
They're connected in parallel, this is so that everything connected to the circuits will receive the same voltage. Also, if everything was connected in series, if one of the components died, everything would be dead (think of christmas lights)
Kirchoff's Voltage and Current Laws apply to all ac circuits?
Kirchoff's Voltage and Current Laws apply to all AC circuits as well as DC circuits. Other laws, such as Ohm's law and Norton and Thevanin equivalents apply equally as well.
The complicating factor is that, at AC, current and voltage are not usually in phase with each other, unless it is a simple resistive circuit. That makes the math harder, but it does not make it invalid or impossible.
What is the effect of increasing the length of the air gap in an induction motor?
The magnetic flux that couples the rotor to the stator will weaken significantly reducing the motor's torque.
What is a capacitor and how does it work?
A capacitor is an electronic device for accumulating and holding a charge of electricity. It consists of two equally charged conducting surfaces having opposite electrical polarity which are separated by a dialectric insulator.
It is a passive electronic component that stores energy in the form of an electrostatic field.
Another Answer
A capacitor is a circuit component that stores energy. It consists of two, parallel, conducting surfaces, called 'plates', separated by an insulator or dielectric. When attached to a d.c. supply, negative charges are transferred from one plate to the other and, if it is then removed from the d.c. supply, the one plate remains negative with respect to the other.
It's a misconception to say that a capacitor 'stores charge', because the amount of charge on the plates remains the same before and after 'charging'! It is more accurate to say that it stores 'separated charges' but, strictly speaking, it's energy that's being stored.
passive two-terminal electrical component used to store energy electrostatically in an electric field this is an instrument that is used to store charge
capasitor is electronic device his work useful for electronic gadjet and also useful electronic machine ther are six type of capasitor ceramic capasitor:"electrolightic capasitor:"plastic film rasistor:"polishtor film rasistor:"propfylin capasitor:"metalesed capasitor
Why capacitor allows ac and not dc?
CAPACITOR BLOCKS DC SUPPLY .THERE ARE MAINLY TWO ANSWERS
1.CAPACITIVE REACTANCE Xc=1/( 2*3.1416*F*C) , HERE THE FREQUENCY OF DC SUPPLY IS ZERO .HENCE THE REACTANCE VALUE IS INFINITY .SO IT BLOCKS THE DC SUPPLY.
2.CURRENT THROUGH A CAPACITOR IS PROPORTIONAL TO THE RATE OF CHANGE OF CURRENT . BUT IN THE CASE OF DC SUPPLY, THE RATE OF CHANGE OF CURRENT IS ZERO. HENCE THE CAPACITOR CURRENT IS ALSO ZERO.
H.L.kiran
Where is a three phase induction motor used?
Usually in commercial or industrial applications such as water pumps or large air handlers.
A small three horse motor can do a lot of work that a DC motor can...which DC used to be stronger than an AC motor would be. But the changing of voltages via a rectifier isn't always practical. But these days the three phase motors have the same torque and horsepower as a DC motor does.
BUT
Most of your three phase motors these days are controlled by a VFD or variable frequency drive which turns the three phases of AC into DC and then pulses it back to simulate an AC signal of various frequencies other than simply 60Hz and thus the motor can have almost any RPM.
The reason is that motors have a high inductance to them and power companies like to charge extra for a highly inductive power consumption. So when using a VFD all the power company will see is the diodes from the bridge rectifier.
What is squirrel cage induction generator?
Squirrel cage type is a type of Induction motor. It tells that the rotor is "squirrel cage" type. Another type of induction motor is with "slip ring" type of rotor.
Squirrel cage type is most widely used Induction motor.
What is the resistance of the circuit if current flow is 6 amperes in a 120-V circuit?
Google Ohms Law. It will give you all the formulas you need to compute Ohms,Volts and Amps. Simple formulas :-)
