there must be a step up transformer and a little chopper circuit
An inductor charges and discharges. When an alternating current come up, the positive signal of the current quickly charges up the inductor. when the negative signal part of the same cycle comes up the inductor develops a potential to opposes it. this is because any charge developed opposes if there is a change or break or whatever for that matter, in supply. so, the negative signal which is basically a change in signal when approaches the inductor the charge developed across it opposes it and as the charge developed thanks to the positive part of the signal is used up to oppose the negative part of the same signal, basically the charge is zero. thus an alternating current or high frequency current for that matter, does not pass through an inductor.CommentI think the above answer has confused inductance for capacitance! No charges are involved with inductors.Whenever current changes in an inductive circuit, a voltage is induced into that circuit. The magnitude of the induced voltage depends on the rate of change of current. The direction of the induced voltage is such that it opposes the change in current -for example, if the current is reducing in value, then the induced voltage will try to maintain that current.
Electronic ballast does not hum as much as a choke. Minute hum of electronic ballast is the small inductor and capacitor producing an oscillation for high voltage generation,
Because the impedance of the inductor and capacitor is not a real resistance / has an imaginary value that causes voltage and current to be out of phase. An inductor's impedance is equivalent to j*w*L (j = i = imaginary number, w = frequency in radians, L = inductance), while a capacitor's impedance is 1/ (j*w*C). The 'j' causes the phase shift.
They are called I squared R losses. That is the formula for calculating power (P) in watts. P=I^2*R. I equals current in amps. R equals resistance in ohms. Also if the voltage (E) is known the formula is P=E^2/R. The current of electrons meets the resistance of the coil wire. That results in heat in inductor and transformer coils.
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.
voltage across inductor create a flux. because of variation current developes an opposite emf.
In an ideal inductor, no, there is no voltage induced across an inductor unless the current in the inductor is changing. However, since there are no ideal inductors nor power supplies, eventually an inductor will draw a constant current, i.e. the limit of the power supply; and, since no inductor has zero ohms at equilibrium, that current will translate to voltage.
depending on the stray capacitance it can be from a few ten volts to a few kilo volts.
Because of Ac supply, current lags voltage by 90 in Inductor.
Eli the ice man. Voltage (E) before Current (I) in a coil (inductor)(L) Current (I) before Voltage (E) in a Cap. (C) Got it?
The voltage is greater than the applied voltage, why?
Yes, with some difficulty. You can think of an inductor as a kind of "AC resistor"in a way. The higher the frequency of the AC, the more difficulty it has passingthrough the inductor.If you apply AC voltage across an inductor, whereV = voltage of the ACf = frequency of the ACL = inductance of the inductor,then the AC current through the inductor isI = V/2 pi f L
Disconnecting a small voltage source from a coil (inductor) causes a larger, often a much larger, reverse voltage spike due to the collapse of the magnetic field in the inductor coupled with the sudden absence of a current path to dissipate the electromagnetic energy. An inductor resists a change in current. The equation for an inductor is ... di/dt = V/L ... which means that the rate of change of current is proportional to voltage and inversely proportional to inductance. If you have a current established in an inductor, and then suddenly open the circuit, the inductor will attempt to maintain that current. It can't, however, because the circuit is open, having large resistance. By ohm's law, voltage is resistance times current. If you keep current constant, and make resistance large, then voltage has to also be large. In the theoretical case of an ideal inductor in an ideal circuit, the voltage spike would have infinite voltage. In practice, we see spikes of several hundred to several thousand volts, depending on the particular cirsumstances.
In a perfect inductor (one with no series internal resistance), the current lags the voltage by 90 degrees. If the inductor has series internal resistance, then the current will lag the voltage by less than 90 degrees - the more the resistance in series with the inductor, the smaller the angle. The tangent of the angle can be found from the ratio of the inductive reactance of the inductor to the DC resistance of the inductor. That is, Tan (phase angle) = (2 x pi x frequency (Hz) x inductance (H)) divided by resistance (ohms) eg, a 1 henry, 100 ohm inductor on 60Hz would give: (2 x pi x 60 x 1) / 100 = 3.77; tan-1(3.77) gives 75 degrees lag of current behind voltage. The cosine of this angle gives the 'power factor' for the inductor - that is, the amount of useful energy dissipated in the inductor. Cos 75 is about 0.25 - so 25% of the energy actually does useful work (heat) - the rest of the energy (75%) is returned to the supply mains when the inductor discharges its magnetic field.
due to change in flux
AnswerWhen you connect DC voltage to an inductor, it opposes the passage of current, which generates a voltage pulse the is several times the value of the applied voltage. When you disconnect the voltage, the electromagnetic field inside the inductor collapses and all the energy it stored is released to the circuit in the form of another large pulse, but this time with opposite polarity.Remember:Inductors oppose changes in current and they store energy in an electromagnetic field.Capacitor oppose changes in voltage and they store energy in an electrostatic field.
For a low frequency source, the voltage across the inductor tends to zero because its impedance is proportionnal to source frequency, whereas the voltage across the resistor tends to the voltage source value.