Transistor will be in OFF mode.
The transistor has three regions, emitter,base and collector. The base is much thinner than the emitter while the collector is wider than both. However for the sake of convenience the emitter and collector are usually shown to be of equal size. The transistor has two pn junctions that means it is like two diodes. The junction between emitter and base may be called emitter-base diode or simply the emitter diode.The junction between base and collector may be called collector-base diode or simply collector diode. The emitter diode is always forward biased and the collector diode is always reverse biased.
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
Zener diode is not a linear device... it is non-linear one. Since linear devices are those devices which have linear characteristics(V-I CHAR.), or follows the Ohm's law i.e. voltage is directly proportional to current. but in case of Zener diode ohm's law fails down. the V-I char. in both forward biased & reverse biased condition is non-linear. So. Zener diode is non-linear device
A: They are both diodes. The difference lies in the application. A rectifier is used to rectify AC current into pulsating current. The zener diode is used to regulate a voltage source to the zener voltage when connected in the reverse direction. ************************************************************** If you look at the characteristic curves of a rectifier diode and a zener diode, you will see that they are similar, but the reverse curve of the zener has a much sharper bend at what is called the "knee". It is at this point on the zener's curve at which it operates.
No. An ordinary diode, be it silicon or germanium, conducts in one direction only, whereas a zener diode conducts in both directions, but at different voltages. An ordinary diode is used to rectify, using its forward bias characteristics, while a zener diode is used to regulate, using its reverse bias characteristics.
Transistor will be in OFF mode.
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.
cutoff
Transistor will be in OFF mode.
The diode is neither shorted nor open. It is a zener diode and it is conducting in both directions. If it were truly shorted, it would read closer to zero ohms in both directions.
The transistor has three regions, emitter,base and collector. The base is much thinner than the emitter while the collector is wider than both. However for the sake of convenience the emitter and collector are usually shown to be of equal size. The transistor has two pn junctions that means it is like two diodes. The junction between emitter and base may be called emitter-base diode or simply the emitter diode.The junction between base and collector may be called collector-base diode or simply collector diode. The emitter diode is always forward biased and the collector diode is always reverse biased.
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
Zener diode is not a linear device... it is non-linear one. Since linear devices are those devices which have linear characteristics(V-I CHAR.), or follows the Ohm's law i.e. voltage is directly proportional to current. but in case of Zener diode ohm's law fails down. the V-I char. in both forward biased & reverse biased condition is non-linear. So. Zener diode is non-linear device
piv:the maximum value of reverse voltage across a diode that occurs at the peak of the input cycle when the diode is reversed-biased.
For the working of TTL nand with totempole When both inputs are LOW The emitter base junctions at A and B gets forward biased, base -collector junction gets reverse biased for Q1.So maximum current flows through forward biased junction. As base -collector junction of Q1 gets reverse-biased, base current through the Q2 is ZERO, which makes Q2 OFF. As Q2 is in OFF state, base current through Q4 is ZERO, which makes Q4 OFF.As Q2 is in OFF state the current through R2 flows through base of Q3 which makes Q3 and diode D to ON.As Q4 is in OFF state the current flows through the load, which make output to go HIGH state
reverse saturation current is produced by the thermal activity of the diode materials. This current: 1- Is temprature dependant; that is, it increases as temprature. 2- Accounts fot the major portion of diode reverse current surface leakage current is produced by contamination on the surface of the device, allowing current flow to bypass the junction