Electronics and Communication Engineering - Electronic Devices and Circuits

21. 

A sample of N-type semiconductor has electron density of 6.25 x 1018/cm3 at 300k. If the intrinsic concentration of carriers in this sample is 2.5 x 1013/cm3 at this temperature the hole density works out to be

A. 106/cm3
B. 108/cm3
C. 1010/cm3
D. 10l2/cm3

Answer: Option B

Explanation:

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22. 

Mobility is directly proportional to Hall coefficient.

A. True
B. False

Answer: Option A

Explanation:

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23. 

n channel FETs are better as compared to p-channel FET because

A. they are more efficient
B. they have high switching time
C. they have higher input impedance
D. mobility of electrons is more than that of holes

Answer: Option D

Explanation:

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24. 

An n channel depletion type MOSFET has

A. lightly doped p substrate and highly doped n source and drain
B. highly doped p substrate and highly doped n source and drain
C. highly doped p substrate and lightly doped n source and drain
D. lightly doped n substrate and highly doped n source and drain

Answer: Option A

Explanation:

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25. 

In a JFET avalanche breakdown occurs when VDS = 22 V and VGS = 0. If VGS = -1 V, the avalanche breakdown will occur at

A. VDS = 22 V
B. VDS more than 22 V
C. VDS equal to or more than 22 V
D. VDS less than 22 V

Answer: Option D

Explanation:

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