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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
Does resistance depend upon current?
The higher the resistance the lower the current flow. It restricts the flow of electrical current. The resistance will not depend upon the current. The current flow will depend on the resistance.
What does a circuit breaker do in car?
Circuit breaker, stops the path of electricity from continuing to it's destination if damage is eminent. For example, some old cars, as I remember, had a 5 amp fuse for the radio. If the mechanic inadvertently installed a 20 amp fuse, the filament in the glass would melt, thus preventing damage to the radio. Also, if the item needed a high amp fuse like a 25, maybe the windshield washer motor (?), and a 5 amp was installed, maybe the 5 amp wouldn't melt but the wipers would operate very slowly, if at all.
The same theory in a house. During a thunderstorm and if the lightning is very close and travels to the house and manages to enter into the electrical system of the house, the main circuit breaker in the fuse box will trip, thus preventing the electricity from damaging the house.
Difference between Diffusion and ion implantation?
diffusion is high temperature process while ion implantation is low temperature process
How do you check the polarity on a car speaker?
With a simple flashlight battery.Connect wires to the speaker then breifly touch the wires to the battery and watch the speaker.If you have positive to positive and negative to negative the speaker will "push outwards" if you have it reversed it will "suck inwards"
Where can you find a drawing for a star delta starter?
This answer needs two parts:
1. The main 3 phase wiring.
2. The control wiring.
To be able to give them, please give more details, such as:
1. Do you have a stop/start button or do you have a pressure switch or remote stop/start?
2. What are the voltages you are working with?
3. Do you need an explanation of how it works and the reasons for wiring in this manner?
For more information, please read the answers to the Related Questions shown below.
Why induction type instrument canot be used for dc measurements?
Induction is a property of voltage changes, which does not occur with Direct Current devices. There are exceptions, such as the coil of an automobile, which charges up to a high voltage between ignition discharges, but the voltage supplying the coil does not vary.
What are the 5 voltages produced by and BTX power supply? +12v -12v +5v -5v +3.3v
WHY does adding more loads in a parallel circuit increase the current?
Adding more loads in a parallel circuit increases the current because of Kirchoff's voltage and current laws, and because of Ohm's law...
1. Kirchoff's voltage law states that the signed sum of the voltage drops around a series circuit is zero. A consequence of this is that the voltages across elements of a parallel circuit must be the same.
2. Ohm's law states that current is voltage divided by resistance. Since the voltage across each new parallel element is the same, the current in that element is known. A consequence of this is that each additional element does not change the current in the other elements.
3. Kirchoff's current law states that the signed sum of the currents entering a node is zero. A consequence of this, and 1 and 2 above, is that the currents added by each parallel element increases the total current entering the set of parallel elements.
Reading this question, one kind of has to guess what's being asked. Here's a statement
that may or may not be helpful to the questioner:
A series circuit is one in which there's never a point where the current has to decide
which path to take. There's never a point where the current can split, and there's only
one possible route all the way through the circuit.
In a series circuit, the magnitude of the current is the same at every point.
What do fuses not protect against?
Fuses protect against too much current flow, but not against high voltage that has a very low current. High voltage can cause damage to circuits if not to wires.
If you put a device in your car, such as a radio, and run a hot wire (wire with current) to the device without putting a fuse in the line, you can have a fire if the line were to short out on something. First the insulation would melt from the unfused wire, smoke going everywhere and there's a terrible smell of burning plastic filling your nostrils. If you're lucky, the wire would be small enough to melt away stopping the electrical parts from heating any further. If not so lucky, you will be the guy on the side of the road everyone is turning their head to see while your car is burning.
Same goes for a house. Everything MUST be fused and to a correct size too.
What is the usage of transformer?
The usage of transformer is to produce electricity from a main electric unit
Why the open and short ckt test of transformer is needed?
The open/short-circuit test on a transformer isn't 'needed'. It's only used if you want to find out the efficiency of a transformer.
Why doesn't current flow through the neutral to earth?
The 'hot' wire delivers current from the power station into the load, which could be any electrical appliance such as, for example, a fridge, a light or a motor.
The 'neutral' wire is there for the specific purpose of carrying the current coming out of the load back to the power station. If the neutral wire was not there, there would not be a complete electrical circuit from the source (power station) to the load and back to the source.
In normal operating conditions the connection from the neutral wire to the Earth does not carry any current.
There should always be 0 V (zero volts) between the neutral wire and the Earth. i.e. no potential difference should ever exist between the neutral wire and the Earth.
The "neutral to earth" connecting wire is fitted to ensure that no part the neutral side of the circuit can develop a high voltage above Earth. If that connecting wire wasn't in place and the circuit had no other protection device (such as a GFCI or RCD) fitted, a very dangerous electrical shock hazard could be present which could electrocute the people using the appliance.
That is why any grounding wires, fitted either to the appliance or to the breaker box, should never ever be cut or removed.
When can be current in a primary coil induce a current in a secondary coil?
Secondary current = Primary current *(Number of secondary turns /Number of primary) turns
AnswerA current isn't 'induced' into the secondary winding of a transformer. It's a voltage that is induced into the secondary winding.
Provided the secondary winding is connected to a load, the secondary voltage then supplies a secondary current which is determined from (Is = Vs/Rload). The primary current then depends upon the value of the secondary current and the turns ratio.
Why LV side is shorted in short circuit test?
Transformer short circuit tests are used to determine the impedances (positive and zero sequence) of the transformer. A simple explanation: to do this one winding is shorted, and voltage is applied to another winding to circulate the normal full load current of the transformer. The impedance of the transformer is the applied voltage divided by the induced current.
If one winding was not shorted, the voltage divided by induced current would not give the impedance of the transformer - the induced current would be much lower, giving a much higher impedance measurement that would be essentially meaningless.
How is electrical power usually measured?
you may need to be more specific. you can measure its amplitude (eg voltage or current), its rate of transfer/use (watts) in ac, its peak , p-p or continuous/rms amount, or the amount used for a unit time ( like watt-hours, kilowatt hours, etc)
Why it is called reduction factor?
it is the fraction the is the highest in value. because it is really small
What are the two common materials used as intrinsic semiconductor?
- silicon
- germanium
- boron nitride
- aluminum phosphide
- gallium arsenide
- indium antimonide
- boron phosphide
- boron arsenide
- boron antimonide
- aluminum nitride
- aluminum arsenide
- aluminum antimonide
- gallium nitride
- gallium phosphide
- gallium antimonide
- indium nitride
- indium phosphide
- indium arsenide
- etc.
There are also other types of semiconductors, like copper oxide, selenium, cadmium sulfide, and lead sulfide. However the properties of these semiconductors are harder to control than those listed above, thus they have few uses in modern electronics.
Carbon in the form of nanotubes or high purity diamond thin films also offers promise as a semiconductor. It should work at much higher temperatures than other semiconductors can, but fabrication problems remain to be solved before it can be used in practical devices.
Why reactive power flow is undesired?
Reactive power is useless part of the energy supplied. A minimum value of reactive power is always required to keep the voltage constant and supply the useful active power. In order to understand the concept completely, do refer PV and QV curves which explains the interdependency of active power, reactive power and voltage.
How to identify a 470 ohm resistor?
Resistors are color coded to denote the value of the resistor as well as the multiplier. In your case a 470 ohm would be colored as Yellow Violet Brown corresponding to 4, 7 and a multiplier of 10^1.
How does a shading coil in a contactor actually work?
A shading coil in a contactor is used to hold the AC contactor's pole faces closed during the transition of the voltage through the zero voltage phase of an electrical cycle.
For an excellent description see related links below.
What is the relationship betweenth the power factor and the load?
No
Load factor is average power consumption rate divided by peak power consumption rate over a period of time. Power companies like customers who have very steady consumption rates ......Load factors approaching 1
Power factor is true power / apparent power (kW/kV.A) and is a measure of how efficiently a customer's load consumes power. Certain types of electrical loads consume power more efficiently ( resistive element heating ) and they have a Power factor approaching 1. Other types of load such as old inductions motor are quite wasteful consumers of power and the utility has to provide more current ( amperage ) for the load to convert to real power
What is the current of a 45 kva transformer?
Presumably, you are asking what is the rated secondary current for a 45 kV.A (not 'kva') transformer? The answer depends on its rated secondary voltage. To obtain the rated secondary current, you divide the (apparent) power rating by its secondary rated voltage.
