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How much time is the maximum positive current behind the maximum positive voltage when the current lags the voltage by 90 degrees?
Wiki User
∙ 12y ago
It depends on the periodic time of the supply which, in turn, is determined by the supply frequency. So, work out the periodic time of a 50 or 60-Hz waveform, and go from there.
Wiki User
∙ 12y ago
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If an AC voltage begins rising or going positive at 0 degrees when will it reach its maximum negative value?
It's a sine wave (if there is no distortion). Voltage is zero at 0 degrees, at its positive peak at 90 degrees, back to zero at 180 degrees, at its negative peak at 270 degrees, and back to zero at 360 degrees.
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.
What is the voltage at the 90 degree point of a sine wave with a maximum voltage of 10 volts?
10 Volts. ANSWER: ASSUMING a start when the voltage is at 0 and 0 degrees at 90 degrees is at maximum at 180 degrees is again at 0 v at 270 degrees is at the maximum negative potential and at 360 degrees is again at 0 v. the voltage is irrelevant in any case but it will follow these rules
How many degrees are the current and voltage out of phase in a pure capacitive circuit?
In a pure (ideal) capacitive circuit, current leads voltage by 90 degrees.
What is the maximum current that can be drawn from a voltage source?
The maximum current that can be drawn from a voltage source is dependent on the impedance of that source, the impedance of the connections to the source, and the energy available from that source.
Why voltage leads in Inductor?
Maximum induced voltage occurs when the current is changing at its greatest rate -this occurs when the current passes through zero. Since this voltage acts to oppose current flow, this maximum voltage acts in the negative sense when the current is acting in the positive direction. Since the supply voltage is equal, but opposite, the induced voltage, it is maximum when the current is zero -so leads by 90 degrees.
Why current lead voltage in coil?
because a coil is an inductor,for current leads voltage in an inductorAnswerIt doesn't! Current lags voltage in a coil. In a purely-inductive circuit, the current lags the supply voltage by 90 degrees. The reason for this is 'self inductance'. Whenever a current changes, a voltage is induced into the coil which opposes that change in current. The maximum self-induced voltage occurs when the rate of change in current is greatest. The greatest positive rate of change of a.c. current occurs when that current is passing through the zero axis of its waveform, so the greatest (negative) induced voltage occurs at thatsame point, which is one-quarter of the wavelength, or 90 degrees. In accordance with Kirchhoff's Voltage Law, the supply voltage must be in antiphase with the induced voltage. So when the peak induced voltage is negative, the peak applied voltage must be positive. Or, to put it another way, the peak value of the applied voltage must occur 90 degrees before the peak value of the current -so the current lags the applied voltage by 90 degrees.
If an AC voltage begins rising or going positive at 0 degrees when will it reach its maximum negative value?
It's a sine wave (if there is no distortion). Voltage is zero at 0 degrees, at its positive peak at 90 degrees, back to zero at 180 degrees, at its negative peak at 270 degrees, and back to zero at 360 degrees.
At what phase angle is the voltage momentarily constant in a sine wave?
We often see the peak and trough (maximum positive and maximum negative excursions) of the sine wave considered as points of momentarily constant voltage. Those points are at phase angles of 90 degrees and at 270 degrees.
Why must the instantaneous current wave be exact 90 degree out-of phase with the applied voltage waveform across an ideal inductor?
Because the voltage induced is proportional to the rate of change of current, and the maximum rate of change of current occurs at the point where the current waveform is 'steepest' -i.e. as it passes through zero. So, as the current passes through zero, the corresponding value of induced voltage is maximum, which means the voltage and current waveforms are displaced by a quarter of the wavelength, or 90 degrees.
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.
What is the voltage at the 90 degree point of a sine wave with a maximum voltage of 10 volts?
10 Volts. ANSWER: ASSUMING a start when the voltage is at 0 and 0 degrees at 90 degrees is at maximum at 180 degrees is again at 0 v at 270 degrees is at the maximum negative potential and at 360 degrees is again at 0 v. the voltage is irrelevant in any case but it will follow these rules
Maximum value of voltage or current?
Amplitude
How many degrees are the current and voltage out of phase in a pure capacitive circuit?
In a pure (ideal) capacitive circuit, current leads voltage by 90 degrees.
The change from negative to positive and from positive to negative in an alternating current?
Is called AC voltage or current.
What is the maximum current that can be drawn from a voltage source?
The maximum current that can be drawn from a voltage source is dependent on the impedance of that source, the impedance of the connections to the source, and the energy available from that source.
What is the maximum voltage across unbiased positive silicon diodes limiter during positive alternation of the input voltage?
0.7 V
