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Electronics and Communication Engineering - Electromagnetic Field Theory

Exercise : Electromagnetic Field Theory - Section 2
16.
In which of the following is the width of junction barrier very small?
Tunnel diode
Photo diode
PIN diode
Schottky diode
Answer: Option
Explanation:

Schottky diode has very small depletion layer.

17.
If the reverse voltage across a p-n junction is increased three times, the junction capacitance
will decrease
will increase
will decrease by an approximate factor of about 2
will increase by an approximate factor of about 2
Answer: Option
Explanation:

Increase of reverse voltage widens the depletion layer and junction capacitance decreases. However the decrease in capacitance is not proportional to increase in voltage.

18.
Which of these has highly doped p and n region?
PIN diode
Tunnel diode
Schottky diode
Photodiode
Answer: Option
Explanation:

Tunnel diode has heavily doped p and n regions leading to very thin depletion layer.

19.
Measurement of Hall coefficient enables the determination of
recovery time of stored carrier
type of conductivity and concentration of charge carriers
temperature coefficient and thermal conductivity
Fermi level and forbidden energy gap
Answer: Option
Explanation:

If a potential difference is developed across a current carrying metal strip when the strip is placed in transverse magnetic field.

Hall effect is very weak in metals, but it is large semiconductors.

20.
The units for transconductance are
ohms
amperes
volts
siemens
Answer: Option
Explanation:

Its units are the same as the units of conductance.

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