Test: The Volt Ampere Characteristics - Electrical Engineering (EE) MCQ

We know that the P-N junction is temperature dependent, it varies with the change in temperature the measure of change that is the voltage equivalent of temperature is given by Vt = T/11600 volts.

Room temperature is 27^o C = 300 k .We know that V_t= T/11600 volts by substituting the value of T we get 300/11600 = 26mV.

At a certain critical voltage, a large reverse current flows and the diode is said to be in breakdown region, at this region the diode will be forward biased and starts to conduct consequently.

The current in the volt ampere characteristics increases exponentially with respect to voltage I(t) = eV(t).

 The cut off voltage is the voltage only after which the semiconductors conduct, the cut off voltage for silicon is 0.7V in the sense the silicon diode will conduct only when voltage is more than 0.7V and 0.3 for germanium.

When there is no external voltage applied on the circuit it acts as an open circuit and there will be no flow of charges hence the current and voltage will be zero.

In the V-I characteristics the change in the current with respect to voltage is very less in depletion region due to the large resistance in the circuit as the resistance deceases by a certain value the current increases exponentially with voltage.

 If the current in the P-N junction diode during forward bias increases beyond the value rated on it will destroy the diode because voltage is directly proportional to current so extreme voltage will burn the diode down.

When the P-N junction is in forward bias that is the p side connected to the positive terminal of voltage source the current in the circuit can be varied by varying the resistance, the current flow decreases as the resistance increases and vice versa.

The P-N junction diode conducts only in forward direction, it will not conduct in reverse direction so only Zener Diode was introduced as it conducts in both forward and reverse direction.