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a diode has two junctions one is doped with p-type and another is doped with n-type.a diode connected in reverse bias means that the n-channel is connected to the positive end of the battery and p-channel is attached to the negative end of the battery
if we start increasing the reverse voltage the width of depletion region increases and the exchange of charge carriers (holes and electrons) is inhibited so we expect zero current in the circuit but on experimental observations we had confirmed that a small current (micro-amp) is observed due to the minority charge carriers(electrons in p-channel and holes in n-channel) present in the diode , for these minority charge carriers the applied voltage appers as as forward bias to them so they conduct .
but on further increasing the reverse voltage we note a large change in the reverse current this is due to junction breakdown (the depletion region is broken , so there is no demarcation between p-channel and n-channel in the diode). the voltage at which this phenomena occurs is called 'break-down voltage'
Wiki User
∙ 11y ago
Wiki User
∙ 11y agoit blocks current flow.
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What is a device made of semiconductor material that acts like a switch controlling the flow of electrons in a chip?
if a diode is in forward biased the diode acts as switch is on and when we apply the diode in reverse biased then it work as the switch as off.
What is an ideal diode?
A: That is no such a diode but if it exists it will have unlimited reverse voltage capability the forward voltage drop will be zero no matter of current flow and it will remain so regardless of temperature changes
Why the current in zener diode is small in reverse biasing and why it is large in forward biasing?
A zener diode is designed to allow a current to flow through it in a direction that is reverse to the normal flow of current that would occur if it were used as a rectifier. Current can flow through a zener diode in both directions. In the forward direction, current will flow at a low voltage, usually about 1 volt. In the reverse direction, no current will flow until the voltage impressed across it is equal to the zener voltage. At this point, a current will flow and an extremely small increase in voltage will cause a large increase in current. Most importantly, it should be noted that the current flow through the zener diode is in the reverse direction to that of a normal rectifier. With the application of sufficient reverse voltage, a p-n junction will experience a rapid avalanche breakdown and conduct current in the reverse direction. Valence electrons which break free under the influence of the applied electric field can be accelerated enough that they can knock loose other electrons and the subsequent collisions quickly become an avalanche. When this process is taking place, very small changes in voltage can cause very large changes in current. The breakdown process depends upon the applied electric field, so by changing the thickness of the layer to which the voltage is applied, zener diodes can be formed which break down at voltages from about 4 volts to several hundred volts.
What is the behavior of a forward and reverse biased diode?
Forward Resistance:def: It is resistance offered by diode to the forward bias is known as forward resistance.This resistance is not the same for the flow of DC as for the changing current. Accordingly this resistance is of two types :1. DC FORWARD RESISTANCE.2. AC FORWARD RESISTANCE.1. DC forward resistance: It is the opposition by diode to the DC. It is measured by the ratio of DC voltages across the diode to the resulting DC current through it.2. AC forward resistance: It is the opposition offered by the diode to the changing current. It is measured by the ratio of change in voltage across diodes to the resulting change in current through diode. The AC forward resistance is more significant as the diodes are generally used with alternating voltage.Reverse Resistance:def: The resistance offered by the diode to the reverse bias is known as Reverse Resistance. It can be DC reverse resistance or AC reverse resistance depending upon whether the reverse bias is direct or changing voltage. Idealy the reverse resistance of a diode is infinte however in practice the reverse resistance is not infinite because for any value of reverse bias, there does exist a small leakage current. It may be emphasized their that reverse resistance is very large compared to the forward resistance.These Definitions are from PRINCIPLES OF ELECTRONICS by V.K MEHTA and ROHIT MEHTA
When both junctions of npn diode are reverse biased?
When p-n junction of a diode reversed biased then majority carriers are not able to cross the junction and are attracted in respective regions.So current becomes approximately zero.But because of minority carriers a reverse current keeps flowing.It is called Reverse Saturation Current.And due to attraction towards sides,charges go away from junction.So width of depletion reason increases.
What is a device made of semiconductor material that acts like a switch controlling the flow of electrons in a chip?
if a diode is in forward biased the diode acts as switch is on and when we apply the diode in reverse biased then it work as the switch as off.
What is the importance of the reverse-to-forward resistance ratio of a diode?
to determine the comparison of resistance value of both forward and reverse diode . The more the resistance the lower the current , the lower the resistance the higher the current . When reverse bias , the resistance is high and it acts in open circuit and the reverse current is very small that can be neglected . When forward bias , the resistance is low and it acts as short circuit and the forward current is increasing as the voltage supply is higher .
When does diode acts as resistance?
When it is forward biased and, in the case of a zener diode, when it is reverse biased as well. It just is not a linear resistance type of device, and the apparent resistance changes as a function of the applied voltage or current.
What is an ideal diode?
A: That is no such a diode but if it exists it will have unlimited reverse voltage capability the forward voltage drop will be zero no matter of current flow and it will remain so regardless of temperature changes
Why the current in zener diode is small in reverse biasing and why it is large in forward biasing?
A zener diode is designed to allow a current to flow through it in a direction that is reverse to the normal flow of current that would occur if it were used as a rectifier. Current can flow through a zener diode in both directions. In the forward direction, current will flow at a low voltage, usually about 1 volt. In the reverse direction, no current will flow until the voltage impressed across it is equal to the zener voltage. At this point, a current will flow and an extremely small increase in voltage will cause a large increase in current. Most importantly, it should be noted that the current flow through the zener diode is in the reverse direction to that of a normal rectifier. With the application of sufficient reverse voltage, a p-n junction will experience a rapid avalanche breakdown and conduct current in the reverse direction. Valence electrons which break free under the influence of the applied electric field can be accelerated enough that they can knock loose other electrons and the subsequent collisions quickly become an avalanche. When this process is taking place, very small changes in voltage can cause very large changes in current. The breakdown process depends upon the applied electric field, so by changing the thickness of the layer to which the voltage is applied, zener diodes can be formed which break down at voltages from about 4 volts to several hundred volts.
What is the behavior of a forward and reverse biased diode?
Forward Resistance:def: It is resistance offered by diode to the forward bias is known as forward resistance.This resistance is not the same for the flow of DC as for the changing current. Accordingly this resistance is of two types :1. DC FORWARD RESISTANCE.2. AC FORWARD RESISTANCE.1. DC forward resistance: It is the opposition by diode to the DC. It is measured by the ratio of DC voltages across the diode to the resulting DC current through it.2. AC forward resistance: It is the opposition offered by the diode to the changing current. It is measured by the ratio of change in voltage across diodes to the resulting change in current through diode. The AC forward resistance is more significant as the diodes are generally used with alternating voltage.Reverse Resistance:def: The resistance offered by the diode to the reverse bias is known as Reverse Resistance. It can be DC reverse resistance or AC reverse resistance depending upon whether the reverse bias is direct or changing voltage. Idealy the reverse resistance of a diode is infinte however in practice the reverse resistance is not infinite because for any value of reverse bias, there does exist a small leakage current. It may be emphasized their that reverse resistance is very large compared to the forward resistance.These Definitions are from PRINCIPLES OF ELECTRONICS by V.K MEHTA and ROHIT MEHTA
Does a zener diode acts as a switch?
A zener diode cannot be used as switch.
Why the negative half cycle cannot pass through the diode?
When the diode is reverse biased a depletion zone is formed at the junction between the cathode and anode, that lacks current carriers (it has neither electrons or holes). Without current carriers, the diode acts as an open circuit, blocking current flow.
What is a diode and how does it work?
When varactor diode is reverse biased then the neutral region between P and N layer increases. When reverse biasing decreases then the neutral region also decreases.
Is elictrical tape an insulator?
yes, the tape acts as an electrical insulator
Is it necessary to add a series resistance with the diode or not?
if the diode is forward biasedwell practically the current flows in a circuit if and only if an effective resistance is present in the circuit, if we consider the diode to be ideal (barrier potential but no internal resistance) in this case an external resistance is required if we use the approximate model (both barrier potential and internal resistance are considered) we need not use an external resistance the internal resistance itself acts as the effective resistance.if the diode is reverse biased:-the same explanation applies even if the diode is reverse biased but one must take care that the reverse voltage drop on diode should not increase the peak inverse voltage mark the diode would be burnt or damaged if this phenomena occurs.So this can be prevented by adding suitable resistance to the circuit through which the voltage drop on diode can be managed
Why photodiode works only in reverse bias not in forward bias?
The fractional change due to intensity on minority charge carriers is more than on majority charge carriers. When light is directly polarized it acts like a normal diode but when reverse polarized its current depends on the brightness (intensity of incident light).
