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Is it true that an alternating current passing through a capacitor While a direct current can not Explain?
Wiki User
∙ 13y ago
Then I'll try this. Just as V=IR is the fundamental equation relating voltage, current and resistance for a resistor circuit, the following equation relates voltace, current and capacitance for a capacitor:
Or, if you are not familiar with that calculus term with the derivative, you can think of it as:
I(t) = C * (change of voltage per time)
So when you have DC, there is no change of voltage with respect to time, so there is zero current. When you have an AC voltage signal that varies across the capacitor with time, that equation lets you calculate the current that results through the capacitor.
A capacitor is two surfaces near each other, but not touching. A direct current "sees" a capacitor as an open switch. It cannot pass through. An alternating current "induces" a charge in a capacitor and can pass through.
Wiki User
∙ 13y ago
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How can a magnet field be produced around a wire?
By passing a current threw it.
High voltage by itself does not produce electric shock What does?
The amount of current passing through your body and the path of the current.
What is current and its unit?
current is the amount of electron charge passing a point in a conductor per unit of time.Its unit is ampere
What is the amount of charge passing a gieven point ever second called?
The current, or electrical current. Measured in Ampères.
What is the unit to describe the amount of electrical current passing through a ponit?
The 'amp'.
What is the use of a capacitor in circuit?
the capacitor is store the charge and used as back up
Does the size of a capacitor matter?
Yes, the size of a capacitor "matters" just as much as the size of a resistor "matters". In both a capacitor and a resistor "size" refers not only to the electrical value of the item but to its current-carrying capacity: a small resistor will burn up if you try to push too much current through it. A big resistor will be able to carry a much higher current than a small one having the same resistance value.Similarly, a small capacitor will be destroyed if you try to push too much current through it and a big capacitor will be able to carry a much higher current than a small one, even if both have exactly the same capacitance value. Capacitance values are measured in Farads (F), microFarads (uF) and picoFarads (pF). Just as a resistor has "Resistance " measured in Ohms, a capacitor has "Capacitive Reactance" or "Impedance", measured in Ohms.The Impedance of a capacitor varies with the frequency of the alternating current passing through it. (This is quite different behavior to a resistor: the Resistance of a resistor does not change with the frequency.) If you look in a book about electrical engineering components you will be able to learn how the Capacitive Impedance is calculated according to the frequency. "The impedance of a capacitor is inversely proportional to the frequency - that is, for very high-frequency alternating currents the reactance approaches zero - so that a capacitor is nearly a short circuit to a very high frequency AC source. Conversely, for very low frequency alternating currents, the reactance increases without bound so that a capacitor is nearly an open circuit to a very low frequency AC source. This frequency-dependent behaviour accounts for most uses of the capacitor." [From Answers.com]
An electric current is the measure of what?
An electric current is a movement of charges, and it is measured in amperes or just amps. An ammeter is used to make this measurement. Current flow is a scalar quantity, and it refers to the number of charges passing a given point per unit of time.
Why does the current lead the voltage across a capacitor by 90 degree rather than lag it?
A: Because a capacitor have to have time to charge to the voltage In a capacitor, the current depends on the voltage difference across it. On AC, this makes it charge, if the voltage is increasing above zero, and discharge if the voltage is reducing towards zero. Because a capacitor has almost no internal resistance, and most loads that it is connected to have only very small resistances in series with the capacitor, the charging and discharging currents depend pretty much on the rate at which the voltage is changing. At the zero crossing point of the sine-wave, when the voltage is actually zero, the rate of change of voltage is very high (the sine-wave is at its steepest), so the current is also very high. If the voltage is positive-going, the current is positive, and if the voltage is negative-going, the current is negative. At the peak of the voltage waveform, the rate of change of voltage is zero or very low (the sine-wave is flat, and not really changing its voltage) so the current is zero, too. Since the maximum positive current occurs when the voltage is passing through zero, going positive, and the maximum negative current happens when the voltage is passing through zero, going negative, the current peaks happen 90 degrees before the voltage peaks, so the current is said to lead the voltage. This is the same as saying the voltage lags the current by 90 degrees.
Is a capacitor a device specifically designed to measure currents?
No, a capacitor is a device that resists the change in electrical potential. It will take and hold a charge based on the value of the capacitor. It's most commonly used to "smooth" direct current or to pass a signal through a wire while passing very little current. There are some interesting circuits produced using capacitors, especially since the capacitors have so many unique properties.
Applications of insulating materials in electrical field?
this stops current from passing between two pieces of the circuit, for example, there is a piece of Dieletric in a capacitor, this is so current cannot travel between the two separate plates, and if there is no current between a positive and a negatice plate then there is not electrical field
What is the phase relationship of voltage across a capacitor and current though the capacitor?
In a capacitor, the current LEADS the voltage by 90 degrees, or to put it the other way, the voltage LAGS the current by 90 degrees. This is because the current in a capacitor depends on the RATE OF CHANGE in voltage across it, and the greatest rate of change is when the voltage is passing through zero (the sine-wave is at its steepest). So current will peak when the voltage is zero, and will be zero when the rate of change of voltage is zero - at the peak of the voltage waveform, when the waveform has stopped rising, and is about to start falling towards zero.
How can charge be produce?
Electrical charge can be produced from an electromagnet. This is a core i.e. iron wrapped in a wire coil. A magnetic device then passing by can cause an electrical charge to be produced, typically AC (alternating current).
Find the power dissipated by an 8.2k resistor if a current of 0.005 amps is passing through the resistor?
0.205 W Power is equal to voltage times current (P=V*I) in Watts, and from Ohm's Law, the voltage across a capacitor is equal to the current passing through it times the resistance (V=I*R). The power is then P=I2R. For a current of 5mA and a resistance of 8.2kOhms, (5*10-3A)2*(8.2*103Ohms) = 0.205 W.
How do you wire a capacitor to a electric motor?
A capacitor resists a change of voltage, proportional to current, and inversely proportional to capacitance. dv/dt = i/c Capacitors can do various things. They can filter out high frequency transients, or power supply ripples, they can block DC while passing AC, they can participate with other components such as resistors and inductors to form filters - the list is endless.
What is mean by zero current switch?
when there is no current passing
Different parameter passing methods with examples?
explain parameter passing methods c program
