1. The magnitude of the electric charge (e) is given by ____________
a) -1.6*10-19 C
b) 1.6*10-19 C
c) 9.11*10-31 C
d) 1.637*10-37 C
Explanation: The charge of the electron is the magnitude of electric force that an electron exerts on other particles which is equal to -1.6*10-19 C, the negative sign indicates the direction of force.
2. What is the forbidden gap voltage for silicon material?
a) 1.46 V
b) 1.56 V
c) 10 V
d) 1.21 V
Explanation: The forbidden gap voltage of a material is numerically equal to forbidden gap energy of the material which is 1.21 joules for silicon so forbidden gap voltage will be 1.21 V.
3. Which of the following parameters of P-N junction diode increases with temperature.
a) Cut in voltage
b) Reverse saturation current.
c) Ideality factor
d) Resistance
Explanation: Reverse saturation current at temperature T2 is 2[(T2 –T1)/10] times greater than reverse saturation current at temperature T1 where T2 is greater than T1
4. Which of the following diodes do not exhibits a constant reverse saturation current with the change in reverse saturation voltage.
a) 1N909
b) 1N405
c) 1N207
d) 1N676
Explanation: 1N207 is the germanium diode for which the reverse saturation current is not constant which the change in voltage due to the leakage in the surface of the diode and due to the generation of new current carriers.
5. Which of these P-N junction characteristics are not dependent on temperature.
a) Junction resistance
b) Reverse saturation current
c) Bias current
d) Barrier voltage
Explanation: As the temperature of the P-N junction increases the current increases and the voltage decreases so the barrier voltage, reverse saturation current, bias current changes with temperature but junction resistance is independent of temperature.
6. As the temperature to the P-N junction increases the current increases due to?
a) Leakage in bias region
b) Electron-hole pair
c) Leakage in P region
d) Leakage in N region
Explanation: As the temperature to the P-N junction increases the mobility of charges increases thus increases the electron-hole pair which proportionally increases the current in the P-N junction diode.
7. By what percentage the reverse saturation current increases with 10 C rise in the temperature.
a) 25%
b) 12.5%
c) 50%
d) 7%
Explanation: As the temperature to the P-N junction diode increases the mobility of charges increases thus increasing the current, the reverse saturation current increases by 7% with 10C rise in temperature and doubles with every 100C rise in temperature.
8. What will be the decrease of barrier voltage with the rise in 10C in temperature?
a) 10V
b) 1mV
c) 10mV
d) 2mV
Explanation: As the temperature to the P-N junction diode increases the voltage across the junction decreases and the current increases with every degree rise in temperature the barrier voltage increases by 2mV.
9. What will be the reverse saturation current in the junction when the voltage across the junction is 0?
a) 0.3A
b) 0.7A
c) 0A
d) 1.24A
Explanation: When the voltage across the junction is zero in the sense there will be potential difference between the junctions hence there will be no movement of electrons and holes, hence the current will be 0.
10. The breakdown voltage of the P-N junction diode decreases due to the increase in.
a) Reverse saturation current
b) Reverse leakage current
c) Bias voltage
d) Barrier voltage
Explanation: Breakdown voltage of the diode is inversely proportional to the reverse leakage current so it decreases with the increase in reverse leakage current.