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What is the reason behind the lag of current in inductor lead in capacitor?
ShaunMarshgp7659
The physics of the energy storage. In an inductor, the current must fight against the stored energy in the magnetic field which tries to keep the current unchanged. Any change in the current lags the voltage since the stored energy impacts the adjustment.
Similarly, the "displacement" current in a capacitor leads the electric field buildup in a capacitor, causing the voltage to lag the current until the stored energy building up in the electric field stabilizes. Any change in the voltage is first preceded by a change in the displacement current.
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Why the voltage drop across inductance and voltage drop across capacitance is greater than source voltage in series resonance circuit?
The reason for the total voltage drops across the capacitance and inductance IN AN AC CIRCUIT has to do with the different phase angles of the voltages.First, current is the same value and same phase angle everywhere in a series circuit. But, voltage across a capacitor lags current by 90 degrees (capacitor current leads voltage). Next, voltage across a pure inductance leads current by 90 degrees (inductor current lags voltage).The rule that all voltages in a series circuit have to add to the supply voltage still applies, but in this case, the voltage drops are added VECTORALLY, not arithmetically. If you were to graph this addition, you would show any resistance voltage in phase with the current, the capacitor voltage at -90 degrees to the current and the inductor voltage at +90 degrees to the current, for a phase difference between them of 180 degrees, cancelling each other out.In a series resonant circuit, the impedances of the capacitor and inductor cancel each other. The only impedance to the flow of current is any resistance in the circuit. Since real-life inductors always have some resistance, at least there is always some resistance in a series resonant circuit.
Why parallel resonance is termed as rejecter circuit?
THE PARALLEL rlc CIRCUIT IS CALLED A REJECTOR CIRCUIT BECAUSE IT REJECTS DOWN THE CURRENT. THE REASON IS AT RESONANCE THE IMPEDENCE OF THE CAPACITOR BECOMES EQUAL TO THAT OF THE INDUCTOR SO NO CURRENT FLOWS. AT LOW FREQUENCY THE CAPACITIVE REACTANCE IS LOW SO ALL THE CURRENT FLOWS THROUGH THE INDUCTOR AND WHEN THE FREQUENCY IS HIGH ALL THE CURRENT WILL FLOW THROUGH THE CAPACITOR BECAUSE AT THAT POINT THE REACTANCE OF THE CAPACITOR IS LOW. SO WE OBTAIN A V-SHAPED GRAPH WITH THE PEAK OF V INDICATING THE REJECTION OF CURRENT IN PARALLEL R-L-C CIRCUIT CIRCUIT,AT RESONANCE,IMPEDANCE IS MAXIMUM AND CURRENT IS MINIMUM.HENCE, SUCH A CIRCUIT WHEN USED IN RADIO STATIONS IS KNOWN AS REJECTOR CIRCUIT BECAUSE IT REJECTS OR TAKES MINIMUM CURRENT OF THAT DESIRED FREQUENCY TO WHICH IT RESONATES.(THIS RESONANCE IS OFTEN REFERRED TO AS CURRENT RESONANCE BECAUSE THE CURRENT CIRCULATING BETWEEN THE TWO BRANCHES IS MANY TIMES GREATER THAN THE LINE CURRENT TAKEN FROM THE SUPPLY.THE PHENOMENON OF PARALLEL RESONANCE IS OF GREAT PRACTICAL IMPORTANCE BECAUSE IT FORMS THE BASIS OF TUNED CIRCUITS IN ELECTRONICS.)A PARALLEL R-L-C CIRCUIT HAS THE PROPERTY OF SELECTIVITY I.E.IT CAN SELECT THE DESIRED FREQUENCY FOR AMPLIFICATION OUT OF A LARGE NUMBER OF FREQUENCIES SIMULTANEOUSLY IMPRESSED UPON IT.FOR INSTANCE IF A MIXTURE OF FREQUENCIES INCLUDING RESONANT FREQUENCY IS FED TO THE INPUT THEN MAXIMUM AMPLIFICATION OCCURS FOR THE RESONANT FREQUENCY.FOR ALL OTHER FREQUENCIES ,THE CIRCUIT OFFERS VERY LOW IMPEDANCE AND HENCE THESE ARE AMPLIFIED TO A LESSER EXTENT AND MAY BE THOUGHT AS REJECTED BY THE CIRCUIT.
Can you change a 440 volt 12.5 uF start capacitor with a 370 volt 12.5uF run capacitor?
There are two ways to read this: you have a burned-out run capacitor on your motor and a good start capacitor in your parts box, and you have a burned-out start capacitor and a good run capacitor. If the run capacitor's bad and you want to put the higher-voltage start cap in its place, the answer is yes. This is called derating, and the only thing it does for you is increases the lifespan of the capacitor because you're not working it as hard as it can take. If the start capacitor's bad, don't do this--they used a 440-volt capacitor in there for a reason.
How current leads voltage?
The reason that current leads voltage in a capacitor is rooted in the way a capacitor works. Picture the capacitor. It's basically two conductive plates separated by a short distance and having a dielectric (insulator) between them. Now, let's specify that our cap (capacitor) is completely discharged and we'll hook it up to a DC voltage source through a switch. Flip the switch on and current will begin to flow, but it is important to look at what happens in just the first instant of time. Electrons will begin to accumulate on the negative plate and their presence there will drive electrons off the positive plate. The capacitor is building up a charge. It is developing a voltage across (or between, if you prefer) the plates. But electrons have to begin to pile onto the plate to actually create the difference of potential (voltage) between the plates. The moving electrons (and that's current) that are piling on the plate are already beginning to flow before the voltage is developed between the plates, so current is said to lead voltage in a capacitor. In a capacitor, the current flowing in it 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 just about 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.
Can a 15uf capacitor replace a 7.5uf?
The answer to this question depends on the application. Generally no - manufacturers of devices design the components precisely, and if they've used a 35uf cap, they've probably done it for a reason. In an audio application the change of a capacitor value will give you a different tonal quality compared to the 35uF cap, though this isn't always a bad thing, though I wouldn't recommend changing it unless you're sure of the effect on the signal. In a power supply application, the capacitors are used to limit something known as ripple current. In this application the higher the capacitor value the lower the ripple current, which is something that is usually a good thing. If you want a more detailed answer i'd need to know more about the circuit you are working on.
Why is the parallel resonant circuit called an rejector circuit?
THE PARALLEL rlc CIRCUIT IS CALLED A REJECTOR CIRCUIT BECAUSE IT REJECTS DOWN THE CURRENT. THE REASON IS AT RESONANCE THE IMPEDENCE OF THE CAPACITOR BECOMES EQUAL TO THAT OF THE INDUCTOR SO NO CURRENT FLOWS. AT LOW FREQUENCY THE CAPACITIVE REACTANCE IS LOW SO ALL THE CURRENT FLOWS THROUGH THE INDUCTOR AND WHEN THE FREQUENCY IS HIGH ALL THE CURRENT WILL FLOW THROUGH THE CAPACITOR BECAUSE AT THAT POINT THE REACTANCE OF THE CAPACITOR IS LOW. SO WE OBTAIN A V-SHAPED GRAPH WITH THE PEAK OF V INDICATING THE REJECTION OF CURRENT.
How the charge oscillate in LC circuit?
If a charged capacitor is connected across an inductor, charge will start to flow through the inductor, building up a magnetic field around it, and reducing the voltage on the capacitor. Eventually all the charge on the capacitor will be gone and the voltage across it will reach zero. However, the current will continue, because inductors resist changes in current, and energy to keep it flowing is extracted from the magnetic field, which will begin to decline. The current will begin to charge the capacitor with a voltage of opposite polarity to its original charge. When the magnetic field is completely dissipated the current will stop and the charge will again be stored in the capacitor, with the opposite polarity as before. Then the cycle will begin again, with the current flowing in the opposite direction through the inductor.The charge flows back and forth between the plates of the capacitor, through the inductor. The energy oscillates back and forth between the capacitor and the inductor until (if not replenished by power from an external circuit) internal resistance makes the oscillations die out. Its action, known mathematically as a harmonic oscillator, is similar to a pendulum swinging back and forth, or water sloshing back and forth in a tank. For this reason the circuit is also called a tank circuit. The oscillation frequency is determined by the capacitance and inductance values used. In typical tuned circuits in electronic equipment the oscillations are very fast, thousands to millions of times per second.
Why the voltage drop across inductance and voltage drop across capacitance is greater than source voltage in series resonance circuit?
The reason for the total voltage drops across the capacitance and inductance IN AN AC CIRCUIT has to do with the different phase angles of the voltages.First, current is the same value and same phase angle everywhere in a series circuit. But, voltage across a capacitor lags current by 90 degrees (capacitor current leads voltage). Next, voltage across a pure inductance leads current by 90 degrees (inductor current lags voltage).The rule that all voltages in a series circuit have to add to the supply voltage still applies, but in this case, the voltage drops are added VECTORALLY, not arithmetically. If you were to graph this addition, you would show any resistance voltage in phase with the current, the capacitor voltage at -90 degrees to the current and the inductor voltage at +90 degrees to the current, for a phase difference between them of 180 degrees, cancelling each other out.In a series resonant circuit, the impedances of the capacitor and inductor cancel each other. The only impedance to the flow of current is any resistance in the circuit. Since real-life inductors always have some resistance, at least there is always some resistance in a series resonant circuit.
What happens when you apply DC directly to a capacitor?
When you apply DC directly to a capacitor, it charges to the value of the DC potential, and then there is (nearly1) zero current flow through the capacitor. If the capacitance is large enough, though, and the DC source has a low enough impedance, the current flow can be quite substantial, damaging things.The reason the equilibrium current is zero is that a capacitor resists a change in voltage, proportional to current and inversely proportional to capacitance...dv/dt = i/c... which makes the capacitor essentially a high pass filter, and a DC blocker.1 The equilibrium current is "nearly" zero because, in our non-ideal world, every capacitor has some leakage current. Practically, the current is zero - from a purist perspective, it is not.
Purpose of capacitor bank on a sub-station electrical room?
The primary reason for a capacitor bank in an electrical substation is for power factor correction. There may also be some secondary purpose for the capacitor bank but the primary reason is power factor correction.
Why parallel resonance is termed as rejecter circuit?
THE PARALLEL rlc CIRCUIT IS CALLED A REJECTOR CIRCUIT BECAUSE IT REJECTS DOWN THE CURRENT. THE REASON IS AT RESONANCE THE IMPEDENCE OF THE CAPACITOR BECOMES EQUAL TO THAT OF THE INDUCTOR SO NO CURRENT FLOWS. AT LOW FREQUENCY THE CAPACITIVE REACTANCE IS LOW SO ALL THE CURRENT FLOWS THROUGH THE INDUCTOR AND WHEN THE FREQUENCY IS HIGH ALL THE CURRENT WILL FLOW THROUGH THE CAPACITOR BECAUSE AT THAT POINT THE REACTANCE OF THE CAPACITOR IS LOW. SO WE OBTAIN A V-SHAPED GRAPH WITH THE PEAK OF V INDICATING THE REJECTION OF CURRENT IN PARALLEL R-L-C CIRCUIT CIRCUIT,AT RESONANCE,IMPEDANCE IS MAXIMUM AND CURRENT IS MINIMUM.HENCE, SUCH A CIRCUIT WHEN USED IN RADIO STATIONS IS KNOWN AS REJECTOR CIRCUIT BECAUSE IT REJECTS OR TAKES MINIMUM CURRENT OF THAT DESIRED FREQUENCY TO WHICH IT RESONATES.(THIS RESONANCE IS OFTEN REFERRED TO AS CURRENT RESONANCE BECAUSE THE CURRENT CIRCULATING BETWEEN THE TWO BRANCHES IS MANY TIMES GREATER THAN THE LINE CURRENT TAKEN FROM THE SUPPLY.THE PHENOMENON OF PARALLEL RESONANCE IS OF GREAT PRACTICAL IMPORTANCE BECAUSE IT FORMS THE BASIS OF TUNED CIRCUITS IN ELECTRONICS.)A PARALLEL R-L-C CIRCUIT HAS THE PROPERTY OF SELECTIVITY I.E.IT CAN SELECT THE DESIRED FREQUENCY FOR AMPLIFICATION OUT OF A LARGE NUMBER OF FREQUENCIES SIMULTANEOUSLY IMPRESSED UPON IT.FOR INSTANCE IF A MIXTURE OF FREQUENCIES INCLUDING RESONANT FREQUENCY IS FED TO THE INPUT THEN MAXIMUM AMPLIFICATION OCCURS FOR THE RESONANT FREQUENCY.FOR ALL OTHER FREQUENCIES ,THE CIRCUIT OFFERS VERY LOW IMPEDANCE AND HENCE THESE ARE AMPLIFIED TO A LESSER EXTENT AND MAY BE THOUGHT AS REJECTED BY THE CIRCUIT.
How do you flow current in capacitor through dielectric?
well actually current doesn't exactly pass through the capacitor or dielectric.Current just flows through the wires connected to the capacitor.The reason is that electric charges are only placed onto capacitor plates and they flow in the circuit and it seems to us that current is flowing in the circuit.Also remember that dielectric only increases the capacitance of a capacitor.AnswerThere are two types of electric current, termed 'conduction current' and 'displacement current', respectively.A 'conduction current' describes the drift of free electrons in a metal conductor. A 'displacement current' describes the polarisation of atoms in dielectrics.When an electric field is applied to a dielectric, the elliptical orbits of the electrons around each atom's nucleus become distorted, and stretch, resulting in polarised atoms. The amount of 'stretch' (polarisation) increases with the strength of the electric field. So, as the voltage across the changes so, too, does the amount of polarisation -i.e. so, too, does the displacement current.So when a capacitor is connected to an external d.c. supply, a varying conduction current drifts around the circuit conductor, while a displacement current occurs within the capacitor's dielectric. When a capacitor is connected to an external a.c. supply, a continuously varying potential difference results in a continuously changing conduction current in the metallic circuit, and a continuously changing displacement current within the capacitor's dielectric.
Is a capacitor with high voltage kV but low capacitance nF dangerous when fully charged?
Most likely not. The duration and current supplied by a capacitor in the microFarad range would be short and small, respectively. On the other hand, of one were touched by the capacitor leads on the eyeball, really thin-skinned areas, or for some reason across the chest over the heart, some damage and/or great pain could happen.
An uncharged capacitor acts like a short circuit when voltage is first applied to it?
Yes it does. Capacitors and capacitor banks have a high inrush current when first energized. As an example this is the reason that VFD's place a resistor in series with the capacitors for a short period of time when they are first energized to prevent damage to the rectification componente. They call it a precharge circuit. Current leads voltage by 90 deg in a purely capacitive circuit.
Are the current BCS standings of now wrong or correct?
today is November 8th 2008:the current BCS standings are not correct REASON:Oklahoma won and moved from 4th to 6th Texas should be behind 6th (exact place is uncertain for me) the reason for behind 6th is because they should be,behind USC and the gators
Why it is necessary to connect ceramic disc capacitor across filter capacitor?
The filter capacitor has inductance and is therefore not very responsive to short term transients, i.e. fast rising or falling current edges. The ceramic disk capacitor, on the other hand, has very little inductance, and therefore is very responsive to short term transients. It is normal "best practices" to connect a small ceramic disk capacitor at each IC's Vcc terminal while also using bulk capacitance in the power supply and at various other places. For the same reason, you want a ceramic disc at the main filter capacitor in the power supply.
What is the reason behind the flow of electric current?
potential difference make the current to flow. i think this can be compared with mechanical system as fluid flow as a result prssure difference between two points
