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When it's forward biased, carrier dffuses from positve terminal of the v source to the negative terminal ". Whereas in reverse bias mode, minority carrier currents are due to thermal energy only. remember: voltage s d amt of energy needed 4 each charge to pass frm 1 pt to the othr pt.
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How does a diode shorted?
due to high voltage across the diode ie more than piv of the diode or current flows more than maximum allowed range of diode.
What is diffusion capacitance in pn junction?
A capacitor is a device that stores charge. Therefore any device that stores charges( static or dynamic) can be said to have capacitance. When a PN diode is forward biased, a current flows due to the majority charge carriers. At a particular instant there will be charges in motion. This is dynamic charge. The capacitance due to storage of dynamic charge is called the diffusion capacitance. We know that C = Q * V. That is capacitance is directly proportional to charge stored. Since the diode current increases exponentially with the voltage applied across it, the dynamic charge also increases exponentially . Hence the diffusion capacitance increases exponentially with the increasing diode voltage.
If a diode is connected to a battery and a lamp what happens when the diode direction is reversed?
I diode allows current to flow in only one direction. Therefore, if a lamp is "on" in a DC circuit, and the diode in series with the lamp is reversed, the light will be turnned off due to the diode blocking current flow (unless the voltage is above the breakdown voltage of the diode - if this is the case, the diode will fail). If this is an AC circuit, every half cycle the diode will turn on, then the next half cycle it will turn off. To your eye, the bulb will most likely appear slightly dim due to this on then off cycling. If the diode is reversed, there will be no apparent change. The difference is the half cycle the diode would have been off before reversing, it will now be on, etc.
When operating as a voltage regulator the breakdown in a Zener diode occurs due to which effect?
avalanche
What is the dependence of reverse saturation current in a P-N diode on applied voltage and temperature?
In a PN junction diode, the reverse current is due to the diffusive flow of minority electrons from the p-side to the n-side and the minority holes from the n-side to the p-side. Hence IS, reverse saturation current depends on the diffusion coefficient of electrons and holes. The minority carriers are thermally generated so the reverse saturation current is almost unaffected by the reverse bias but is highly sensitive to temperature changes. so , as the temperature increases the density of minority charge carriers increases creating a slight increase in the amount of IC.so, the inference is reverse current is directly proportional to temperatureIn the reverse biased condition the PN diode is least dependent on voltage till certain limit called breakdown voltage, till that voltage the increase in V is not actually increasing the current it is just increasing the heat at the junction which in turn raises the temperature and so the minority charge carriers.But if the voltage increases the breakdown voltage the pn junction is lost and all the holes and electrons will start acting like charge carriers , such avalanche of charge carriers increases the current sharply to several hundred times. This phenomena is called as zener or avalanche breakdownso if applied voltage less than breakdown voltageno significant change in reverse current(only due to minority charge carriers)and if applied voltage greater than breakdown voltagethe pn junction break and current increases sharply (both due to minority and majority charge carriers)
How does a diode shorted?
due to high voltage across the diode ie more than piv of the diode or current flows more than maximum allowed range of diode.
What is diffusion capacitance in pn junction?
A capacitor is a device that stores charge. Therefore any device that stores charges( static or dynamic) can be said to have capacitance. When a PN diode is forward biased, a current flows due to the majority charge carriers. At a particular instant there will be charges in motion. This is dynamic charge. The capacitance due to storage of dynamic charge is called the diffusion capacitance. We know that C = Q * V. That is capacitance is directly proportional to charge stored. Since the diode current increases exponentially with the voltage applied across it, the dynamic charge also increases exponentially . Hence the diffusion capacitance increases exponentially with the increasing diode voltage.
When current through a zener diode increases by a factor of 2 by what factor does the voltage across the zener diode increase?
If the zener diode is in zener breakdown the voltage across the zener diode remains constant regardless of current (for the ideal zener diode). Real zener diodes have parasitic resistance that causes the voltage across the zener diode to increase slightly with increased current, but due to temperature dependant variations in this parasitic resistance as well as temperature dependant variations in the zener breakdown voltage, this change in voltage in real zener diodes cannot be described by a simple linear factor.
Why is the current in diodes only due to diffusion and not influenced by electric field of batteries?
In diodes there are two types of current namely diffusion and drift current. Former one is due to concentration gradient of majority carriers (hole in p side n electron in n-side). Due to this difference of concentration of carriers majority carrier start to diffuse in other side. The amount of diffusion is just depends on concentration. Contrast to this, drift current which is very small in compare to diffusion current depends on the applied voltage across the diode. Since total current is mainly due to diffusion in forward biased hence it is not too much effected by battery's electric field. I dint know that batteries have electric field. INTERESTING.
Why the graph of reversed biased diode is lies in third quadrant?
-- The definition of 'reverse bias' is anode negative with respect to the cathode, or negative voltage across the diode. That places the graph in negative-x territory. -- The diode simply acts as a resistor. Its unique 'diode' characteristics arise from the fact that its 'resistance' changes with different bias points, but the current through it always has the same polarity as the voltage across it. Therefor . . . -- When the voltage across it is negative, the current through it is also negative. Negative current appears on the graph in negative-y territory. -- Negative-x territory/negative-y territory is the third quadrant.
How does a semiconductor diode work?
A semiconductor diode allows current to flow in only one direction due to its asymmetric semiconductor junction. When a forward bias voltage is applied across the diode, it allows current to flow freely. However, when a reverse bias voltage is applied, it blocks current flow due to the depletion layer widening and creating a high resistance barrier.
What is the definition of diffusion current?
Diffusion current is current that is generated due to the vibration of electrons.
Why diode conducts current in forward bias but does not conduct in reversed bias?
diode current flows only when the diode is forward biased because in reverse bias the barrier potential increases. Diode can conduct in reverse bias if applied votage is high enough to overcome the reverse bias barrier potential but it can be destructive.
Why does the load voltage still goes slightly negative with the freewheel diode conntected?
The load voltage can still go slightly negative with the freewheel diode connected due to the inductive nature of the load. When the power supply is turned off, the inductor generates a back EMF, causing the voltage across the load to drop below zero. The freewheel diode allows current to circulate through the inductor, but it may not fully clamp the voltage to zero, especially if there are any parasitic elements or if the diode has a forward voltage drop. As a result, the voltage can momentarily dip into the negative range.
If a diode is connected to a battery and a lamp what happens when the diode direction is reversed?
I diode allows current to flow in only one direction. Therefore, if a lamp is "on" in a DC circuit, and the diode in series with the lamp is reversed, the light will be turnned off due to the diode blocking current flow (unless the voltage is above the breakdown voltage of the diode - if this is the case, the diode will fail). If this is an AC circuit, every half cycle the diode will turn on, then the next half cycle it will turn off. To your eye, the bulb will most likely appear slightly dim due to this on then off cycling. If the diode is reversed, there will be no apparent change. The difference is the half cycle the diode would have been off before reversing, it will now be on, etc.
Why there is no current in reverse bias condition?
Current flows in a reverse biased diode because diodes are not ideal. They do have leakage current and a breakdown voltage in reverse, just as they have a breakdown current in forward and a non-linear and non-parallel forward voltage to current curve. It is also possible that you are looking at a zener diode. A zener diode is specifically design to conduct at a certain voltage in reverse.
What is the special properties of a diode?
in the negative biasing it gives the constant voltage irrespective of limited current.......the voltage it provides in the negative biasing is known as 'zener voltage' due to this property zener voltage is used as voltage regulator........voltage regulator is a circuit which gives constant output even the input is changing.
