1. Consider two energy levels : E1, E
eV above the Fermi level and E2, E eV below the Fermi level. P1
and P2 are the probabilities of E1 and E2
being occupied by the electron respectively. Then
a. P1 > P2
b. P1 = P2
c. P1 < P2
d. P1 and P2 depend on number of free electrons
Solution : https://www.youtube.com/watch?v=XrZAi2Q0S7Q
2. In an intrinsic semiconductor, the free electron concentration depends
on
a. Effective mass of electrons only
b. Effective mass of holes only
c. Temperature of the semiconductor
d. Width of the forbidden energy band of the semiconductor
Solution : https://www.youtube.com/watch?v=C61o_nRoaBc
3. According to the Einstein relation, for any semiconductor, the ratio of
diffusion constant to mobility of carriers
a. Depends upon the temperature of the semiconductor
b. Depends upon the type of the semiconductor
c. Varies with life time of the semiconductor
d. Is a universal constant
Solution : https://www.youtube.com/watch?v=CNsSUnfw85Q
4. Direct band gap semiconductors
a. Exhibit short carrier lifetime and they are used for fabricating BJTs
b. Exhibit long carrier lifetime and they are used for fabricating BJTs
c. Exhibit short carrier lifetime and they are used for fabricating LASERs
d. Exhibit long carrier lifetime and they are used for fabricating LASERs
Solution : https://www.youtube.com/watch?v=fzNBPuE9hEE
5. The diffusion capacitance of a PN junction
a. Decreases with increasing current and increasing temperature
b. Decreases with decreasing current and increasing temperature
c. Increases with increasing current and increasing temperature
d. Does not depend on current and temperature
Solution : https://www.youtube.com/watch?v=YgQjfNh4JiU
6. The pinch off voltage for an n-channel JFET is 4 volts, then pinch off
occurs for VDS when VGS = -1 volts is
a. 3 volts
b. 5 volts
c. 4 volts
d. 1 volts
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