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ECE :: Electronic Devices and Circuits

  1. Before doping the semiconductor material is

  2. A.
    dehydrated
    B.
    heated
    C.
    hardened
    D.
    purified

  3. The atomic number of silicon is 14. It can be therefore concluded that

  4. A.
    a silicon atom contains 14 protons
    B.
    a silicon atom contains 14 neutrons
    C.
    a silicon atom contains 14 electrons
    D.
    all of the above

  5. X-rays cannot penetrate through a thick sheet of

  6. A.
    wood
    B.
    paper
    C.
    lead
    D.
    aluminium

  7. Ohmic range of metal film resistors is

  8. A.
    1 to 100 ohms
    B.
    10 to 1 K ohms
    C.
    100 to 1 M ohms
    D.
    100 to 100 M ohms

  9. The current density J, free electron mobility μn, hole mobility μp , magnitude of free electron and hole concentration ni electric field E and charge on electron e, in intrinsic semiconductor are related as

  10. A.
    J = (μn + μp)eniE
    B.
    J =
    C.
    J =
    D.
    J =

  11. In order to achieve good stabilization in potential divider method current I1 through R1 and R2 should be

  12. A.
    I1 > 20 IB
    B.
    I1 > 15 IB
    C.
    I1 < 5 IB
    D.
    I1 > 10 IB

  13. A sample of N type semiconductor has electron density of 6.25 x 108/cm2 at 300 K. 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

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

  15. Addition of 0.3 to 3.5% silicon to iron

  16. A.
    increases the electrical resistivity of iron
    B.
    decreases the electrical resistivity of iron
    C.
    does not change electrical resistivity of iron
    D.
    silicon can't be added with iron

  17. A bistable multivibrator

  18. A.
    has no stable state
    B.
    has one stable state
    C.
    has two stable state
    D.
    none of the above

  19. Transconductance indicates the

  20. A.
    control of output voltage by input voltage
    B.
    control of output current by input voltage
    C.
    control of input voltage by output current
    D.
    control of input current by input voltage