# Electronic Devices and Circuits Questions and Answers – Qualitative Theory of the p-n junction

This set of Electronic Devices and Circuits Interview Questions and Answers for freshers focuses on “Qualitative Theory of the p-n junction”.

1. The donor ions is represented by a positive plus sign. Is it True or False?
a) True
b) False

Explanation: The donor atom donates the extra ion to the semiconductor. Therefore, it is represented by the positive plus sign.

2. Initially, the p-type carriers are located to the____________of the semiconductor.
a) Right
b) Left
c) Middle
d) Top

Explanation: The p-type carriers are nominally located to the left of the junction and n-type carriers are to the right.

3. The displacement of the charges results in
a) Magnetic field
b) Electric field
c) Rust
d) Hall effect

Explanation: The flow of carriers in a semiconductor results in the electric field across the junction. The electric field thus makes the current flow in the device.

4. What is the value of 1 micron?
a) 10-6cm
b) 10-5cm
c) 10-4cm
d) 10-3cm

Explanation: 1 micron=10-4cm=10-6cm.

5. Which of the following results when the equilibrium established in a semiconductor?
a) Restrain the process of diffusion
b) Electric field becomes very high
c) Both a and b
d) None of these

Explanation: As the electric field is very high, the flow of the carries will be restricted and the equilibrium will be obtained.
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6. Which of the following options doesn’t defined for the necessity for the existence of the potential barrier?
a) Contact
b) Potential
c) Diffusion
d) Fermi dirac

Explanation: The potential barrier is formed at the junction of the semiconductor. It’s necessity of the potential barrier is known as the contact, potential or diffusion.

7. Under the open-circuited conditions the net hole current must be zero. Is this statement is True or false?
a) True
b) False

Explanation: The net hole current is zero because if this wasn’t true, the hole density at one end of the semiconductor would continue to increase indefinitely with time, a situation which is obviously physically impossible.

8. The un-neutralised ions in the neighbourhood of the junction are known as
a) Depletion charges
b) Uncovered charges
c) Mobile ions
d) Counter ions

Explanation: The un-neutralised ions in the neighbourhood of the junction are known as uncovered ions because they are not mobile.

9. Which of the following doesn’t defines for the junction which is depleted of mobile charges?
a) Depletion region
b) Uncovered region
c) Space charge region
d) Transition region

Explanation: The junction which is depleted of mobile charges is known as depletion region or space charge region and transition region.

10. Convert 10 micron to meters.
a) 10-5m
b) 107m
c) 10-6m
d) 10-4m

Explanation: Since, 1 micron=10-6m
10 micron =10-5m.

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