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What happens to the voltage across a capacitor as it discharges?
Wiki User
∙ 11y ago
well to get the answer first know the principle by which a capacitor(consider a capacitor without dielectric) gets charged .let a capacitor with plates p1 and p2 and resistor in parlell are connected to a DC source , when the switch is closed the circuit is in ON state and current starts flowing ,assume the flow of current as the movement of negative charges then the concept would be much clear.
assume that p1 is connected with positive terminal of the battery and p2 with the negative terminal ,now as the switch is closed the negative charge on p1 is attracted by the positive terminal of the battery and is driven to the other plate p2 of capacitor.as this process continues charge seperation increases and potential difference starts getting developed and after a very long time the potential diff. across capacitor becomes equal to the applied voltage V.
during discharging first of all we short the battery , this mplies that we are short circuiting plates p1 and p2 so again charge redistribution takes place and after a longtime both the plates become electrically nuetral
Wiki User
∙ 11y ago
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Why do resistor voltage decrease while capacitor discharges?
The reason why resistor voltage decreases while a capacitor discharges is because the resistor acts like a source of electrical energy. As the capacitor discharges, it draws energy from the resistor, which causes the voltage across the resistor to decrease. This is because the capacitor is acting like a drain, and is taking energy out of the resistor, thus causing the voltage across the resistor to decrease. The resistor and capacitor work together in order to create a discharge circuit. This is done by connecting the capacitor to the resistor, and then to a voltage source. The voltage source supplies the energy to the resistor, and then the resistor transfers this energy to the capacitor. As the capacitor discharges, it takes energy from the resistor, which causes the voltage across the resistor to decrease. In order to understand this process better, it is important to understand the basics of Ohm's Law. Ohm's Law states that the voltage across a resistor is equal to the current through the resistor multiplied by the resistance. As the capacitor discharges, it takes energy from the resistor, which means that the current through the resistor decreases, and therefore the voltage across the resistor will also decrease.
When a circuit consists of a capacitor and a resistor in series with a voltage source and the voltage across the resistor becomes zero then the capacitor is?
fully charged.
What happens when lagging Power Factor changes to leading PF?
when lagging Power Factor changes to leading PF, then the voltage across the circuit in which capacitor bank is connected, is increased.
How is the capacitor able to account for AC Ripples?
Ripple Voltage is voltage variation across the load and it is the AC component. To answer this question, consider a Half Wave rectifier with a smoothing capacitor: This rectifier will consist of a sinusoidal voltage source, an ideal diode, a capacitor in parallel with the load. At t=0, the voltage across capacitor = load voltage When the circuit is switched on, the capacitor is fully charged as the sinusoidal source reaches its peak. However, the sinusoidal nature causes the source voltage to decline after reaching the peak. This means that no current will flow through the diode. But the capacitor is still charged. So this will supply current to the load while it discharges. But during the discharging period (till the sinusoidal picks up again), the load voltage is an exponential function = peak voltage *exp-[(t - t')*resistance of load*capacitance] Now a key point is that the pulsating current is flowing through the diode to recharge the capacitor. Because of this constant charge and discharge of the capacitor in the cycle, the load voltage has AC ripples. At the same time load current is never zero and is directly prop to load voltage. The dc component >> ac component and the ripple voltage is greatly reduced by the capacitance esp a large one. You can minimize these by choosing a large capacitance. This is how a capacitor accounts for AC ripples. You can never actually rid these ripples even if you use a full-wave rectifier! Google search half - wave rectifier graphs on the ripples to understand this!! --- Sona
How capacitor used in a timing circuit?
A capacitor relies on the time it takes for the voltage across it to reach a certain value. When it is fully discharged, it acts like a piece of copper wire. ie: it conducts. The voltage across it now is zero. When a voltage is applied to it, it begins to charge, and so the voltage measured across it's terminals increases. This takes time. How much time depends on the voltage applied resistor connected to it and the value of the capacitor.This voltage is then used to energies a relay, turn a transistor on, fire an SCR, and lots of other things.
Why does the voltage reading drop in measuring the potential difference across the capacitors?
Because the capacitor discharges. so voltage across the capacitor decreases.
Why do resistor voltage decrease while capacitor discharges?
The reason why resistor voltage decreases while a capacitor discharges is because the resistor acts like a source of electrical energy. As the capacitor discharges, it draws energy from the resistor, which causes the voltage across the resistor to decrease. This is because the capacitor is acting like a drain, and is taking energy out of the resistor, thus causing the voltage across the resistor to decrease. The resistor and capacitor work together in order to create a discharge circuit. This is done by connecting the capacitor to the resistor, and then to a voltage source. The voltage source supplies the energy to the resistor, and then the resistor transfers this energy to the capacitor. As the capacitor discharges, it takes energy from the resistor, which causes the voltage across the resistor to decrease. In order to understand this process better, it is important to understand the basics of Ohm's Law. Ohm's Law states that the voltage across a resistor is equal to the current through the resistor multiplied by the resistance. As the capacitor discharges, it takes energy from the resistor, which means that the current through the resistor decreases, and therefore the voltage across the resistor will also decrease.
What happens to the charge if you double the voltage across a capacitor?
In order to double the voltage across a capacitor, you need to stuff twice as much charge into it.
What happens to the current in a circuit as a capacitor charges?
What happens to the current in a circuit as a capacitor charges depends on the circuit. As a capacitor charges, the voltage drop across it increases. In a typical circuit with a constant voltage source and a resistor charging the capacitor, then the current in the circuit will decrease logarithmically over time as the capacitor charges, with the end result that the current is zero, and the voltage across the capacitor is the same as the voltage source.
How do you charge a capacitor?
You charge a capacitor by placing DC voltage across its terminal leads. Make sure when using a polarized capacitor to place positive voltage across the positive lead (the longer lead) and negative voltage across the negative lead. Also make sure that the voltage you charge the capacitor to doesn't exceeds its voltage rating.
What happens to current flow in a capacitive when the DC voltage across the capacitor is approximately equal to the source voltage?
As long as you don't exceed the breakdown voltage of the capacitor ... which is marked right on it ... DC voltage on it produces NO current flow through it. Only AC 'appears' to flow through a capacitor, and even that appearance is bogus when you really get down to it.
Will voltage drop across a capacitor?
basically a capacitor will charge to the input DC level however it will mathematically never happen since capacitors charge at a certain rate the voltage drop across a capacitor will follow the R C time constant or 63% of the applied voltage for a unit time.AnswerIn the case of an a.c. supply, yes, there will be a voltage drop across a capacitor. In the case of an 'ideal' capacitor, this will be the product of the load current and the capacitive reactance of the capacitor.
What two facctors determine the capacitive reactance of a capacitor?
The reactance of a capacitor is a function of -- the capacitance of the capacitor -- the frequency of the voltage across the capacitor
When a circuit consists of a capacitor and a resistor in series with a voltage source and the voltage across the resistor becomes zero then the capacitor is?
fully charged.
What does the volt on a capacitor mean?
the voltage number on the capacitor indicates that the capacitor can with stand to that particular voltage across it.generally during design, the value of capacitor will be selected in such a way that this voltage rating should be double than what really we get in the circuit
Why ac voltage is always applied across capacitor?
It's not.
Why does ac fails in capacitor?
Capacitors can pass alternating current provided the current and the voltage are within the capacitor's rating. Very often there is a dc bias voltage across the capacitor as well as the ac voltage, so the peak voltage must not exceed the limit. Electrolytic capacitors must not have a reverse voltage across them in any circumstances, because this can cause failure.
