1. When a forward biased is applied to a diode, the electrons enter to which region of the diode?
a) P-region
b) N-region
c) P-n junction
d) Metal side
Explanation: When the forward biased is applied, the electrons enter to the p-region and the holes enter to the n-region so that holes can flow from p-region to n-region. Whereas, the electrons can travel from n-region to p-region.
2. The number of injected minority carriers falls off linearly with the increase in the distance from the junction.
a) True
b) False
Explanation: The number of minority carriers fall off exponentially rather than linearly with the increase in the distance from the junction.
3. What is the total current in a diode when x=0?
a) I = Ipn (0) – Inp (0)
b) I = Ipn (0) + Inp (0)
c) I = -Ipn (0) – Inp (0)
d) I = -Ipn (0) + Inp (0)
Explanation: At junction, the total current is equal to the minority hole current plus the minority electron current.
4. The current in the diode is
I. Unipolar
II. Bipolar
a) I only
b) II only
c) I and II both
d) Neither I nor II
Explanation: The current in the diode consists of both the electrons and holes. So, it is bipolar.
5. The current is constant throughout the device.
a) True
b) False
Explanation:The current in the device is constant but the proportion due to the electrons and holes varies with distance.
6. Which of the following statements is correct under forward biased p-n diode?
a) current enters n side as hole current and leaves p side as electron current
b) current enters n side as electron current and leaves p side as hole current
c) current enters p side as hole current and leaves n side as electron current
d) current enters p side as hole current and leaves p side as electron current
Explanation: When the current flows in a p-n diode, the current enters p side as hole current and leaves n side as electron current.
7. Calculate the total current when Ipn (0)=1mA and Inp (0)=2mA.
a) 1mA
b) -1mA
c) 0
d) 3mA
Explanation: I=Ipn (0)+Inp (0)
=1mA+2mA
=3mA.
8. What is the hole current in the p region of the diode?
a) Ipp (x)=I-Inp (x)
b) Ipp (x)=I+Inp (x)
c) Ipp (x)=-I-Inp (x)
d) Ipp (x)=-I+Inp (x)
Explanation: The hole current in the p region is equal to the total current minus the minority electrons in the p region.
9. What does Inp represent?
a) Hole current in n region
b) Hole current in p region
c) Electron current in n region
d) Electron current in p region
Explanation: Inp constitutes of the electron current in the p region. It is the minority electron carrier in the p region.
10. Deep into the p side the current is a drift current Ipp of holes sustained by the small electric field in the semiconductor. Is the statement true or false?
a) True
b) False
Explanation: In the p region, the drift current is sustained into the p region by the small electric field which is formed at the junction in the semiconductor. So, the above statement is true.