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The initial condition is the voltage and/or current existing at the time a mathematical solution begins. Example: what happens when a resistor is connected across a capacitor? well, you say that at t=0 the resistor is connected, then after that the voltage across the capacitor is v0.exp(-t/RC), where v0 is the starting voltage, t is the time, R is the resistance and C is the capacitance. This simple solution needs only one initial condition which is the starting voltage v0 across the capacitor.

Linear differential equations are common in electrical engineering and a complete solution of one (such as the example) always requires one or more initial conditions.

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Q: What are the initial conditions for voltage across the capacitor and current through the inductor in the dc steady state?
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How surge current is produced in a capacitor input filter?

Being that the capacitor appears as a short during the initial charging, the current through the diodes can momentarily be quite high. To reduce risk of damaging the diodes, a surge current limiting resistor is placed in series with the filter and load.


A capacitor is discharged through a 80 ohm resistor. The discharge current decreases to 29 percent of its initial value in 2 seconds. What is the value of the capacitor?

14 micro farads @ 1.4 seconds.. idk what it is at 2 seconds ;p


What is the differencebetween a run capacitor and start capacitor?

The run capacitor is used when the load is functional while the start capacitor is used to produce the initial torque to drive the load.


Does the current in a pure capacitive circuit lead or lag the applied voltage?

Answer #1Just remember our friend ELI the ICE man! E is voltage, I is current, L is inductance, and C is capacitance. ELI In an inductively reactive circuit (L), the voltage (E) comes first, then the current (I) lags behind. ICE In a capacitively reactive circuit (C), the current (I) leads, then the voltage (E) comes later. Note that while your assumption (in the stated question) is correct, an engineer or electrician would not say it that way. The voltage waveform is the constant, and the current waveform is said to lead or lag. This is because reactive or non-linear loads distort the current. If you look at a power-factor meter, and it says leading or lagging, it is referring to the current. It would be more accurate to re-phrase your question: In a capacitive reactive circuit does the current lead the voltage? Yes! Answer #2: Another method I learned from one of my EE professor is that in an inductor the current lags the voltage because the electrons get dizzy going through all of those loops (coils) in the inductor and "lag" behind the voltage.


Why won't a capacitor conduct DC?

capacitor blocks DC, after it finishes charging. Actually, it resists any CHANGE to DC (ie ac), after it has finished charging. IRT the actual question, current will always flow, as long as there is a closed circuit.

Related questions

What is the initial condition of the elements capacitor and inductor that have no initial energy stored?

The initial condition of a capacitor that has no energy stored is zero volts. The initial condition of an inductor that has no energy stored is zero amperes.


Suppose no energy given to inductor and a decreasing current is applied to it. emf will be produced and energy is given by it.so i think energy is not stored in inductor. it is its own property?

How do you propose to connect a decreasing current to the inductor ? The initial current through the inductor is zero, and you want to connect it to a current which is not zero and decreasing. At the instant you make the connection, the inductor current is zero, and it must rise to the non-zero value where you want it to begin decreasing. The current in the inductor cannot change from zero to something in zero time. As it rises from zero to the initial value, guess what . . . the inductor is storing energy in its magnetic field, while producing the usual voltage equal to [ L di/dt ].


Is inductor linear or non linear when the initial in it is non zero taking output as current and input as voltage?

Linear


What happens when closing and breaking an inductive circuit?

When you close an inductive circuit, since an inductor resists a change in current, the initial reaction of the load is to look like a high resistance. As current builds, the resistance falls. With a theoretical source and inductor, current would eventually reach infinity, that is after infinite time, but practical sources and inductors will reach a plateau current. When you open an inductive circuit, again, since an inductor resists a change in current, the inductor attempts to maintain that current, but there is no conductivity for that current so, the inductor presents a high voltage spike in the reverse direction it was initially "charged" with. With a theoretical inductor, and theoretical infinite impedance, the voltage spike would be infinite. Again, practical inductors have a maximum voltage spike, but this spike can still be quite high, even thousands of volts, which can damage the circuit, so it is important to maintain a conduction path for the collapsing field, often a diode, or a resistor/capacitor filter.


Why initial current is always zero in an inductor and if it is due to 100 percent opposition then current should always remain zero because just after opposition current is zero than again?

When initially closing a switch into any electrical device, the initial condition will be zero current. I think you are getting confused about impulse response. An impulse (such as would result from closing a switch) is essentially a very short, high frequency wave. Inductors' impedance is equivalent to the wave frequency (in radians)*2*PI*inductance (in Henrys). You can see if the applied waveform is a very high frequency, the inductor's response will be to highly limit current flow. A capacitor's impedance is equivalent to 1/(frequency*2*Pi*capacitance); the impulse response of a capacitor is a very high current spike due to a very low impedance.


Why reactance does not oppose DC?

An ideal inductor does not oppose the steady flow of current because it has no resistance. But it opposes changes in the current and the voltage across the inductor is the rate of change of current (in amps/second) times the inductance in Henrys, which is how inductance is defined. So when a battery is connected across an inductor the initial rate of rise of the current is V/L amps/sec, where L is the inductance, and it continues to rise until limited by any resistance in the circuit.


How surge current is produced in a capacitor input filter?

Being that the capacitor appears as a short during the initial charging, the current through the diodes can momentarily be quite high. To reduce risk of damaging the diodes, a surge current limiting resistor is placed in series with the filter and load.


Why inductor does not allow the sudden change of current?

an inductor has inductance(L). its unit is henry. when any change in currentin a inductor occurs it produces an self induced emf equal to e=-Ldi/dt volt. minus(-) sign indicates the direction of the induced voltage which is in opposition to the cause which is producing it. here the case is change in current(di/dt). that's why, whyan inductor opposes any change in voltage and hence current in it.


A capacitor is discharged through a 80 ohm resistor. The discharge current decreases to 29 percent of its initial value in 2 seconds. What is the value of the capacitor?

14 micro farads @ 1.4 seconds.. idk what it is at 2 seconds ;p


What is the differencebetween a run capacitor and start capacitor?

The run capacitor is used when the load is functional while the start capacitor is used to produce the initial torque to drive the load.


What is capacitive effect in antenna?

The capacitive effect is an element's opposition to a change in AC voltage. The resistor will develop a positively charged current at it flows through a capacitor. This will prevent a change in the initial voltage.


Can voltage flow with no amperage?

First of all, voltage doesn't flow. Voltage sets up an electric field. If the ends of this electric field are connected by a conductor, then current flows. So, if the question is "Can voltage exists with no current flow" the answer is Yes, for example a battery or a charged capacitor (although there may be some initial current flow to establish the electric field (e.g. charging the capacitor)). An electric field exists between the poles of the battery or capacitor. Current doesn't flow until the ends of that field are connected by a conductor (e.g. a light bulb).