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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.

500 Questions

What is control program?

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Asked by Wiki User

the computer is what runs the car and all the engine functions, you can change the functions of the engine to get more power by buying a performance programmer and downloading the program into the cars computer.

theres your answer :)

What is induction time?

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Asked by Wiki User

12 noon

'why can't we determine barrier potential by using a voltmeter connected across the ends of a diode'?

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Asked by Wiki User

The barrier potential is not a voltage created inside the diode. instead, it refers to the depleted zone around the juncture.

Since this region is deplete from carriers (electrons or holes), it became a virtual isolator. In order to make the depleted zone conductive, you need to apply an external voltage to the diode terminals.

If the voltage is in forward bias (+ to the anode and - to the cathode), you will need 0.2/0.3 V for germanium diodes and 0.6/07 V for silicon diodes. You need an external diode to keep the forward current with safe limits.

If the voltage is in reverse mode (- to the anode and + to the cathode), you will need to apply much more voltage to achieve conduction, although this could permanently damage the diode. Zenner diodes, for instance, always work in reverse bias to create a stable voltage, which is used for regulation purposes.

What is the resistance of human skin?

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Asked by Wiki User

Measurements and research from various sources tell us that

-1mA is the sensibility threshold.

-5mA to 10mA hurts.

-40mA causes heart disturbance.

-60mA to 100mA is lethal.

These are reactions of a healthy human body. Much lower currents could be lethal for persons with heart malfunctions, pacemakers or other implanted electronic devices.

See related links for my source.

The resistance of human skin is highly variable depending on several different variables, but the two main variables are whether the skin is clean or dirty. Clean skin often has a resistance of about 500 ohms. Dirty skin can have electrical resistances of up to several million ohms.

What happens if you add more batteries to a circuit?

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Asked by Wiki User

Depends on how you add them. Added in series, the voltage will increase, maybe to the point of damaging the LED. If the LED survives, it will shine brighter.

Added in parallell, the LED will shine the same, and will be able to shine longer before draining the batteries.

How do you find the power factor with true and apparent power?

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Asked by Wiki User

to put out the power fector you have to divided apparent power with true power.

Answer

You can determine the true power of any load using a wattmeter. To find the apparent power, you use a voltmeter to measure the supply voltage and an ammeter to measure the load current, and multiply the two readings together.

If you then want to go on to find the power factor, then you divide the true power by the apparent power. If you want to find the reactive power you use the following equation:

(reactive power)2 = (true power)2 x (apparent power)2

What is the Difference between resistive and reactive load?

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Asked by Wiki User

A resistive load is one which does not power a motor. Examples of resistive loads would be light bulbs, toasters, stereo systems, televisions, hot plates and convection heaters. To calculate the wattage required to run these items, simply multiply input amps x volts for each individual item, then add those figures together to get the total wattage required. For example, 5 light bulbs at 60 watts each would be a total of 300 watts. If you want to add a 1500 watt hot plate, your total is now 1800 watts. Adding some music from a radio would add another 100 watts, and so on. • A reactive load is one that is usually associated with some type of electric motor. Examples of reactive loads would be circular saws, furnace motors, water pumps and air conditioners. This type of load may take three times the rated power requirement to start up and perform the required work. An example of this would be an air conditioner that runs on 20 amps at 120 volts. The running watts would be calculated.

Circuit diagram of RC coupled amplifier?

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Asked by Wiki User

One of the several uses of an RC coupled amplifier is to amplify the given input signal. It makes use of a sinusoidal input signal.

What are some examples of piezoelectric materials?

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Asked by Wiki User

This is a crystal which, when squeezed, will generate a potential difference across opposite faces. A practical example is an inexpensive phonograph/gramophone pickup.

If the resistance in the circuit is increased what will happen to the current and voltage?

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Asked by Wiki User

* resistance increases voltage. Adding more resistance to a circuit will alter the circuit pathway(s) and that change will force a change in voltage, current or both. Adding resistance will affect circuit voltage and current differently depending on whether that resistance is added in series or parallel. (In the question asked, it was not specified.) For a series circuit with one or more resistors, adding resistance in series will reduce total current and will reduce the voltage drop across each existing resistor. (Less current through a resistor means less voltage drop across it.) Total voltage in the circuit will remain the same. (The rule being that the total applied voltage is said to be dropped or felt across the circuit as a whole.) And the sum of the voltage drops in a series circuit is equal to the applied voltage, of course. If resistance is added in parallel to a circuit with one existing circuit resistor, total current in the circuit will increase, and the voltage across the added resistor will be the same as it for the one existing resistor and will be equal to the applied voltage. (The rule being that if only one resistor is in a circuit, hooking another resistor in parallel will have no effect on the voltage drop across or current flow through that single original resistor.) Hooking another resistor across one resistor in a series circuit that has two or more existing resistors will result in an increase in total current in the circuit, an increase in the voltage drop across the other resistors in the circuit, and a decrease in the voltage drop across the resistor across which the newly added resistor has been connected. The newly added resistor will, of course, have the same voltage drop as the resistor across which it is connected.

What is the name of the transformer that reduces the voltage?

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Asked by Wiki User

a step down transformer is used to lower the voltage from the powerlines into your home. a common slang term for this type of transformer is a pole pig.

What is the resistance of the circuit conductors when the conductor voltage drop is 3 volts and the current flowing through the conductors is 100 amperes?

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Asked by Wiki User

you have to use Ohm's law here. But first If you are not sure about currents or electricity in general then dont go messing about... 20 thousandths of 1 ampere applied across the heart can be enough to kill a man.

100A will kill you instantly no questions asked!!!!

Be safe.don't touch and if any doubt you must always contact a trained and registered electrician or electronic engineer.

And now the question.

V = IR

V is the voltage (potential difference or voltage drop) measured in volts.

I is the current measured in amperes ( symbol A )

and R is the resistance in Ohms ( symbol is the Latin Omega letter)

first rearrange the equation: R = V/I

now plug the figures into the equation:

R = 3/100

the answer is: 0.03 ohms.

I don't think you will be able to get a supply that delivers 3V at 100A though.

How do you connect two twelve volt batteries for my motor home?

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Asked by Wiki User

You will want to connect them in "parallel" (positive to positive, negative to negative). If you connect them in "series" (positive to negative) you will add one voltage to the other, making 24 volts.

Explain the necessity for the use of a starter with a dc motor?

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Asked by Wiki User

In its simplest form, the starter of a dc motor is a variable resistance in series with the armature circuit of dc motor to reduce the high starting current so that the armature winding does not get overheated and burnt while the motor isgetting started. As the rotating armature of dc motor picks up speed, the starter resistance is gradually reduced so that the motor is able to attain its full speed when the starter is not expected to offer any additional resistance in series with the armature winding of the dc motor. At full speed the motor starts running normally, of course, without the help of starter. In other words, the starter offers resistance to armature current during starting of dc motor only. Under normal working condition of dc motor , the starter is electrically out of armature circuit of the motor. The starter protects the armature of dc motor from getting damaged. The electromotive force (emf) induced in the armature winding during starting builds up from zero value to max value to restrict the armature current within the permissible value at full speed. As the speed of armature/motor build up, armature induced emf also starts building thus reducing the role resistance offered by the starter, hence requiring it to gradually reduce as the motor picks up full speed.

What is used to increase or decrease the voltage across a power line?

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Asked by Wiki User

The device that increases or decreases the voltage impressed across a power line is known as a voltage regulator.

A voltage regulator is a type of transformer where the primary and secondary turns ratio are fairly close; one (primary or secondary) often has a tap changing ability to add or remove several windings, allowing more dynamic control of voltage.

Who was Mr Ohm of Ohm's Law?

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Asked by Wiki User

The law was named after the German physicist Georg Ohm who, in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire.

What is the voltage of a battery if it is connected across an 8 ohm resistor and 0.75 amps of current flows through the resistor?

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Asked by Wiki User

The battery has 6 volts across its terminals. The way to discover it is to apply Ohm's law. It (Ohm's law) comes in 3 "flavors" that look a bit different but all say exactly the same thing. Here they are: E = I x R [Voltage equals current times resistance.] I = E/R [Current equals voltage divided by resistance.] R = E/I [Resistance equals voltage divided by current.] In these equations, voltage is E, current is I and resistance is R. They are measured in units of volts, amperes (or amps) and ohms, respectively. In your problem, we have the resistance (R) and the current (I). We need to find the voltage (E), and the formula E = I x R is the logical choice to discover the voltage. As E = I x R here, E = 0.75 x 8 = 3/4 x 8 = 6 volts. Piece of cake.

How can you increase voltage of an ac adapter?

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Asked by Princeofexcess

Increase primary voltage but decraease amerage - eg double voltage and half amperage. This will double your secondary voltage. "Transformed" voltage is easy to understand by following this simple math rule.

secondary voltage divided by primary voltage = no of turns on secondary and no of turns on primary.

eg;

240v \ 12v = 20 (factor)

this means the secondary winding is 20x the primary winding. Basically thats all I know Stick to this rule for step up & step down tranforming & you'll be sweet.

What is the formula of electric current?

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Asked by Wiki User

the formula for electric current is VI ,where v is voltage then I is the current.

the unit used for current is ampere and volts for voltage. multiply the total I to the Voltage

The formular of electric current is given by I=V/R ,I=P/V

If a diode is connected to a battery and a lamp what happens when the diode direction is reversed?

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Asked by GordonMorse27

I diode allows current to flow in only one direction. Therefore, if a lamp is "on" in a DC circuit, and the diode in series with the lamp is reversed, the light will be turnned off due to the diode blocking current flow (unless the voltage is above the breakdown voltage of the diode - if this is the case, the diode will fail). If this is an AC circuit, every half cycle the diode will turn on, then the next half cycle it will turn off. To your eye, the bulb will most likely appear slightly dim due to this on then off cycling. If the diode is reversed, there will be no apparent change. The difference is the half cycle the diode would have been off before reversing, it will now be on, etc.

Which increases or decreases the voltage of alternating current?

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Asked by Wiki User

(i) EMF (Electro Motive Force) the source of voltage can increase or decrease voltage.

(ii) Load connected can increase or decrease voltage (In case of overload voltage reduces.)

(iii) Resistance of wire - I R loss ( Voltage drop V = IR)

What is an AC generator?

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Asked by Wiki User

An AC generator is an electrical machine which produces alternating current electricity. It must be turned by a prime mover which can be an internal combustion engine - driven, usually, by diesel oil or gasoline - or can be a turbine, driven either by superheated steam or by water falling from a reservoir. (The latter is known as "hydro-electric power generation").

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Alternating voltage may be generated by rotating a coil in the magnetic field or by rotating a magnetic field within a stationary coil. That kind of system is called an AC generator or an "alternator".

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An a.c. generator, which is usually called an 'alternator', is a machine which converts kinetic energy into electrical energy. Its output is an alternating voltage.

For more information see the answers to the Related Questions shown below.

If you remove one of two bulbs connected to a circuit in a series will the other bulb still shine?

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Asked by Wiki User

if you have 2 bulbs and one burns out, the other wont shine,

if you remove 1 bulb, you are breaking the circuit, and the current

cant flow to the second bulb, so no it wouldn't shine.

Why a DC motor is called DC motor?

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Asked by Wiki User

DC, in DC motor, is an acronym for Direct Current, which means that it works on direct electrical supply by a battery. In an AC motor, the motor runs on Alternating Current Supply from other sources other than batteries, such as electricity from your house.

No, d.c. is not an acronym. It is simply an abbreviation.

"a word formed from the initial letters or syllables taken from a group of words"

http://www.thefreedictionary.com/acronym

Yes, a word. "dc" is not a word.