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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
According to Ohm's Law how is voltage related to resistance and current?
1). Voltage = (resistance) x (current)
2). Current = (voltage) / (resistance)
3). Resistance = (voltage) / (current)
I think #2 is Ohm's original statement, but any one of these can be massaged algebraically
in order to derive the other two.
Can dc current work on transformer?
Transformer is by definition can transform only AC current. But it's possible to build device that can step up or step down DC voltage directly. These are called DC-DC converters not transformers.
A dry cell uses chemicals that are in solid or powder form, as opposed to lead acid batteries that use a liquid electrolyte. The term is generally used to refer to standard non-rechargeable batteries.
How do you convert a 50 micro-amp DC meter to a 100 milli-amp meter?
with a resistor 300K in series with the 50 micro amperes DC meter
What happen to the energy stored in the capacitor while the capacitor is discharging?
It flows out of the capacitor into the external circuit
How current electricity moves in a circuit?
You need a source of electrical potential difference, also known as voltage (which is the technical term for what for you call "electric pressure"). The easiest and most common voltage source is a household battery. Hook up the positive electrode of the battery using a conductor (eg. a copper wire) to one end of your circuit and the negative electrode to the other end, and voila, you'll have electric current flowing through your circuit.
What is the total resistance in a parallel circuit with a 10 ohm lamp and a 15 ohm lamp?
Well, first of all, it's the current that's "going through" the wire, not the voltage.
The voltage is just the difference in pressure between the two ends, and that's
what makes the current want to go through it, towards the lower pressure. But
we understood what you meant in the question.
From Ohm's Law, [ I = E/R ] . (Current = voltage divided by resistance.)
I = (10)/(5) = 2 amperes.
You might not want to try this at home. The power dissipated by the wire is
P = I2 R = (2)2 (5) = 20 watts.
That's quite a bit of power for a piece of wire or a common resistor to dissipate.
The little round resistors with the color stripes that you see everywhere are
rated 1/4 watt, 1/2 watt, or 1 watt. One of those will pop if it tries to radiate
20 watts, and a piece of wire with 5-ohms will glow a nice hot bright red color.
Why use half wave rectification and what are its advantages over full wave rectification?
A full-wave rectifier will provide an output through both the positive and negative halves of the AC sine wave. The half-wave rectifier will only provide an output for half the cycle. The filtered outputs of both rectifiers can be "smoothed" well, but the higher the load on the half-wave rectifier, the more the output voltage will vary across a cycle of input power. This results in higher ripple and makes regulation a bit more difficult. The full-wave rectifier will provide an output through both the positive and negative halves of the sine wave. It effectively "inverts" the negative half of the cycle and provides two "pulses" of power per cycle as opposed to one pulse per cycle for the half-wave rectifier. The full-wave rectifier might use a pair of diodes and a center tapped transformer, or might use four diodes in a full wave bridge configuration and a transformer with no center tap.
Equation for resistance in a circuit?
Resistance is the opposition to the flow of electric current through a conductor. It is defined as the ratio of the potential difference (volts) between the ends of the conductor to the magnitude of the current (amps) through the conductor.
What are the uses of De-solder Guns?
De-soldering gun is used for removing molten solder, defective components, altering, and salvaging high value components in a circuit for possible re-use.
What is distribution transformer?
Distribution transformers change the feeder voltage to utilization voltage required by the consumer. they are essentially step down transformer which changes the voltage to standard service voltage. their rating is about 200KVA.
since these transformers are operated throughout a day, eventhough they r not carrying load r not, it should hav a good ALL DAY EFFICIENCY .
Why capacitor does not allow DC?
In order for a capacitor to pass current, the voltage across it must be changing. In a DC circuit, the voltage does not change so, at equilibrium, the capacitor is effectively an open circuit.
We also call this DC blocking. You can take a signal with DC bias on it, perhaps because it came from a class A BJT amplifier, couple it with a capacitor, and the signal will make it through, but the DC bias will not.
How do electrical transformers work?
To do its magic on the high voltage and change it to low voltage the electrical transformer uses two rather intriguing and important phenomena. Firstly whenever an electric current flows, there is magnetism around it. Secondly whenever a magnetic field changes (by moving or by changing strength) a voltage is made. If there's a wire close by when this happens then a current will flow in the wire as the magnetism changes.
The electrical transformer takes in high voltage electricity and lets it run through lots of coils wound around an iron core. Because the current is alternating the magnetism in the core is also alternating. Also round the core is an output wire with less coils. The changing magnetism generates a current in the wire and less coils means less voltage. So the voltage is 'stepped-down'.
Answer#1...Wire produces a magnetic field when current is passed through it. If you wrap the wire around something (a core) to make a coil, it concentrates that field. The core isn't actually necessary but it helps concentrate the field and make the transformer more efficient.#2...If you pass a magnetic field through a wire, it produces electron flow.
If you make a coil with 100 wraps and pass current through it, it will produce the magnetic field. If you have another coil close enough to be IN that magnetic field, and it has 10 turns, you will get about 1/10 the voltage from the second coil that you put into the first one.
It gets a lot more complicated than that with formulas and all kinds of mathematics, but that is the basics of a "step down" transformer.
AnswerWhen an electron travels through a conductor it generates "ripples" in a fluid like medium (EMF) those ripples induce the electrons in conductors in close proximity to move(=current). In a transformer electrons in the input or primary side travel around the core perpendicularly causing the electrons in the core to spin(the core resembles a doughnut like shape) the secondary coil gets induced by the motion of electrons in the core. The a out put voltage is determine by the turns ration of the primary to secondary coils. In the mechanical world an electrical transformer is like a car transmission, converting torque (current) into speed(voltage) or vies versa. Total input power= Total output power.One. Measure the load resistance. Divide by five. Use that as the added series resistance. (For 1000 ohm load, add 200 ohms in series.)
Note that this answer may be wrong for situations where the load resistance changes or the current is high, as you must consider source to load rejection ratio and power consumed by the added resistor.
Another way is to to get a stabilised plug top power unit . Open it up and use the electronic regulator from it. Wire your 6 volts DC in place of the transformer secondary and use output as normal. The integrated three terminal regulator you are looking for is called a 7805 industry standard 1 amp regulator.
ANSWER: Must know the load current first then add a series resistor to drop 1 volts with the current flow.
yes it is
230 v is deadly, it doesn't matter if it's ac or dc.
Some people say one is more dangerous than the other. That implies that there is some voltage, lower than 230 v, at which one will kill you but the other will not. There is no conclusive evidence for that, so it can't be said that ac is more dangerous than dc or vice versa.
Why a bjt is called a current control device?
The collector current is a multiple of the base current due to the inherent design of the BJT. In circuit analysis, barring knowing the exact amplification, I've used 50 many times - so if you have 20 uA flowing in the base, the collector current should be ~ 1mA, and the emmiter will be ~1.02mA.
Who was the actress in Short Circuit?
The cast of Short Circuit - 1986 includes: Tim Blaney as Number 5 John Garber as Otis Steve Guttenberg as Newton Crosby Marguerite Happy as Barmaid Sergio Kato as Frank Robert Krantz as Reporter Howard Krick as Farmer Shay McLean as Party Guest Brian McNamara as Frank Austin Pendleton as Howard Marner Billy Ray Sharkey as Zack Mary Reckley as Party Guest Penny Santon as Mrs. Cepeda Ally Sheedy as Stephanie Speck Fred Slyter as Norman Herb Smith as Gate Guard Jan Speck as Reporter Fisher Stevens as Ben Jabituya William Striglos as Party Guest Barbara Tarbuck as Senator Mills Jack Thompson as Party Guest Vernon Weddle as General Washburne
What is the reason of voltage drop in electrical circuit?
Whenever current passes through a resistance of some kind, a voltage drop occurs across that resistance. The amount of the drop is given by Ohm's Law:
V=IR
V = The value of the voltage drop
I = The current through the circuit in amperes
R = The total resistance of the circuit
Let's say you have a simple series circuit containing a 10-volt battery, a 3-ohm resistor, and a 2-ohm resistor in series with each other (if the resisitors are in parallel the voltage drop across the "system" of resistors is equivalent to the input voltage of the system, in this example 10 volts. The current flow through each resistor can then be calculated using Ohm's Law). Ohm's Law tells us that 2 Amps are flowing in the circuit (I = V/R = 10/5 = 2). The voltage drop across the 3-ohm resistor is 6 volts (V = IR = 2*3 = 6).
Conductors are insulated to prevent the escape of energy from within them. Without insulators, the conductors will usually release energy into the surrounding substance, unless that substance acts as an insulator. This answer is the result of recollection of a KS3 (high school) science class, and, although quite vague, it is a good outline. It will be useful to search "conductors and insulators" in a search engine, as there will be much more information provided.
Difference between voltage and potential difference?
Voltage is (potential energy). Energy is the amount of work that the electrical current can perform... total watts. Voltage is just a potential. An electric spark can jump a distance through air, and the distance is determined by voltage. A full description would take quite a bit of time and space on this web site, but some physics or other science books can certainly give an adequate description of the relationship between Volts, Amps and Watts, and give meaning to the formula: Volts X Amps = Watts
What are disadvantages of a digital multimeter?
The main advantage of a digital multimeter over an analog multimeter is their accuracy.
AnswerDigital instruments are not necessarily more accurate than analogue instruments (although they often are), but they are far more robust and, usually, far easier to read without error. A digital multimeter has no moving parts and is unaffected by gravity, so they can be used at any angle, whereas analogue instruments needed to be placed on horizontal surfaces and not subjected to vibration.
Connect the two batteries for the voltage needed. If they are 12 volt batteries and the lights are 12 volts, connect the batteries in parallel (negative to negative and positive to positive). If they are 12 volt batteries and the lights are 24 volts, connect the batteries in series (negative of one battery to positive of the other). Run a wire from batteries to first switch, then to two of the lights and the other switch (in parallel). From the second switch run a wire to the third light, then connect all three lights back to the battery.
Where can you find a series circuit?
A lamp A fan and a bunch of other things
AnswerThe classic example of a series circuit is a string of Christmas-tree lights. They are connected in series if, when one lamp burns out, all the lights go out.
How can you measure the resistance?
It is done with an instrument called a megohm meter or megger. On the whole megger testing is non destructive. What happens is a DC voltage is applied to the device or winding under test. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to it. On my megger there are 3 ranges 300V, 750V, and 1000 volts. Applying the proper voltage is essential to not damaging the device you are testing. Working voltages up to 240 volts should use the 300 range. Working voltages up to 600 volts use the 750 volt range and working voltages above 600 use the 1000 volt range. As you can see if you used the 1000 volt range on a device that had a working voltage of say 24 volts you could damage the insulation just by testing it. So meggering a device is non destructive if you use the tester as its instructions tell you to.
What happens when voltmeter is connected in parallel?
An ideal voltmeter has infinite impedance(resistance). If you were to break the circuit and put it in series and try to make a measurement, it is easy to see that the circuit would act completely differently and your measurement would be wrong. An ideal ammeter is always connected in series because it has 0 resistance, so all of the current would flow through it, and not through the wire that you are trying to measure the current of.
A better answer though is to think about what you are trying to measure. When you say something is 3 Volts, that is a difference between the voltages at two different points. If you want to see what the voltage drop across a resistor is, for example, you need to put one probe of the voltmeter on one side of the resistor and the other probe on the other side of the resistor. That setup is simply called being in parallel.
Voltage is potential difference between two points, hence measured across or in parallel, where as current is measured in series since current flows (*)
