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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
What does voltage current mean?
V=IR, voltage is directly propostional to current and resistance (by ohm's law).
CommentVoltage is not 'proportional to resistance'. Resistance is a constant, and is not affected by voltage at all.
How much voltage and current is given to homes?
Typically in the US, voltage is +/- 110-120 volts AC RMS (so you can get 240 total), and a typical service will be 100 Amps (I believe, but I could be wrong on "typical" here). This doesn't mean the home uses 100Amps, it means this is the peak amount the home is allowed to draw.
The function and use of an ammeter and a voltmeter?
A: ACTUALLY they are both the same just the application makes one or the other. Their function is to measure potential difference on a load or circuitry
Can you run a 380v 3-ph 50 Hz motor on a 460v 3-ph 60hs supply?
You have to reduce the voltage by a factor 50/60 to avoid saturation in the active iron of the motor. Accordingly the available max load of the motor is reduced by (50/60)^2. Nevertheless the actual load of the motor is defind by the requirements of the driven machine (pump, elevator, etc). The nominal speed of the motor is reducet too.
Can you switch a 220 microfarad capacitor with a 100 microfarad capacitor?
This depends on the application. It may be OK to do so, or it may result in problems. If this is an already designed circuit, and you have a 820u cap that has blown, I suggest replacing with a 1000u (in my experience, this is more common and readily available), AND i usually up the voltage rating on the cap.
Capacitors typically blow due to overvoltaging or reverse polarizing them. If they've blown before, it's likely you'll have similar problems again, which is why i go with bigger, and higher voltage rated. I hate reduing things repeatedly.
How do you install a capacitor?
It gets hooked up like a switch would be. The main power wire goes to the positive side on the cap and a short power wire comes off of the positive side of the cap to go to the amp. Ground comes from car metal to the negative side of the cap and a short ground comes off of that negative to go to the negative on the amp.
Does the current stay the same in a parallel circuit and a series circuit?
A series circuit allows only one path for the electron path to follow. This type of circuit is found in something like Christmas tree lights. But a parallel circuit allows the 2 or more path for the electron path to follow. This is primarily used in households. So no, they are not the same electrons because they are two completely different circuits.
Why does resistance decrease in a parallel circuit?
That's true. This is because when there are several resistors in parallel, the electrons have additional paths to choose from - it becomes "easier" for them to get through. This is what the resistance expresses. You can also play around with the formula for parallel resistance:
1 / R(total) = 1 / R1 + 1 / R2 + 1 / R3 ...
Try this out with some numbers. For two resistances, an equivalent is: R(total) = (R1 * R2) / (R1 + R2).
What is an isolation transformer?
An isolation transformer does not have a direct electrical path from the power input side to the power output side. The term is also used to define how much electrical isolation exists between the input and output windings. For example when using line-voltage input transformers to power low voltage device handled by humans, a high degree of isolation is required for safety.
Isolated transformers often use separate bobbins for the primary and secondary coil windings, but usually the windings are just wound on top of each other with insulation in between.There is usually an electrostatic shield between windings which is tied to transformer case.
Non-Isolated transformers are becoming rare. A common example is the "Variac" which is a non-isolated variable transformer. Usually the term "auto-transformer" is used to describe non-isolated transformers. They are rarely found in consumer products.
Although any transformer with a separate primary and secondary winding is an isolation transformer to some extent, The term is usually used to denote a special-purpose transformer built just for that use. It is tested and rated to withstand a very high voltage difference, called the withstand voltage, so that even if thousands of volts are applied to the primary, it will not leak through to the protected side. These transformers are used in the medical industry, to protect patients hooked up to monitoring instruments that are powered by utility mains, as well as other uses.
An 'isolation transformer' is a transformer specifically used to electrically-isolate the secondary circuit from the primary circuit. Of course, ALL mutual transformers do this, but an isolation transformer normally has a 1:1 ratio, which means its secondary voltage is the same as its primary voltage. In other words, its purpose is NOT to change the supply voltage, but to isolate the user from the supply circuit.
Isolation transformers isolate the secondary circuit from the earthed (grounded) primary circuit. As there is no earth return from the secondary circuit back to the primary supply, isolation transformer eliminate the risk of shock between the secondary circuit and earth.
An example of an isolation transformer is a bathroom shaver socket. The output is completely isolated from the earthed supply, so users cannot receive a shock between the outlet and earth.
When one bulb is unscrewed in a series circuit does the other bulb stay lit?
You break the circuit and they both extinguish (go out).
Answer: The circuit will open up causing the current to quit flowing to both bulbs therefore there will be no lighted bulbs
CommentYou also have the full supply voltage appearing across the empty lampholder!
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.
