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  • Question

  • The specific gravity of tungsten is 13.8 and its atomic weight is 184.0 Assume that there are two free elements per atom. Then the Fermi level or characteristic energy for the crystal in eV will be


  • Options
  • A. 8.95 eV
  • B. -8.95 eV
  • C. 7.326 eV
  • D. -7.326 eV

  • Correct Answer
  • 7.326 eV 

    Explanation
    A quantity of any substance equal to its molecular weight in grams is a mole of that substance contains the same number of molecules as one mole of any other substance. This Avogadro's number and equals 6.02 x 1023 molecules per mole. Thus

    The specific gravity of tungsten is 13.8 and its atomic weight is 184.0 Assume that there are two fr

    The specific gravity of tungsten is 13.8 and its atomic weight is 184.0 Assume that there are two fr

    The specific gravity of tungsten is 13.8 and its atomic weight is 184.0 Assume that there are two fr

    = 9.03 x 1028 electrons/m3

    Since for tungsten the atomic and the molecular weights are the same. Therefore for tungsten

    EF = 3.64 x 10-19(?)2/3

    = 3.64 x 10- 19(9.03 x 1028)2/3

    EF = 7.326 eV.

    Exam Questions Papers problems

    Search Results

    • 1. For a = - 1, find the value of V2

    • Options
    • A. ?
    • B. 0
    • C. V1
    • D. none of the above
      • Discuss
    • 2. In a 4 bit weighted resistor D/A converter, the resistor value corresponding to LSB is 32 k?. The resistor value corresponding to MSB will be

    • Options
    • A. 32 K?
    • B. 16 K?
    • C. 8 K?
    • D. 4 K?
      • Discuss
    • 3. Consider the system with and where p and q are arbitrary real numbers. Which of the following statements about the controllability of the system is true?

    • Options
    • A. The system is completely state controllable for any non zero values p and q
    • B. Only p = 0 and q = 0 result in controllability
    • C. The system is uncontrollable for all values of p and q
    • D. We cannot conclude about controllability from the given data
      • Discuss
    • 4. In a flash type ADC, employing 15 comparators resolution with 10 volts reference; is expected to be :

    • Options
    • A. 0.625 V
    • B. 0.656 V
    • C. 0.525 V
    • D. insufficient data
      • Discuss
    • 5. Consider the following

      1. Maximum energy of electrons liberated photoelectrically is independent of light intensity
      2. Maximum energy of electrons liberated photoelectrically varies nonlinearly with frequency of incident light.

    • Options
    • A. (1) is true and (2) is false
    • B. (1) and (2) both are true
    • C. (1) is false and (2) is true
    • D. (1) and (2) both are false
      • Discuss
    • 6. As the temperature increases the mobility of electrons __________ .

    • Options
    • A. decreases because the number of carries increases with increased collisions
    • B. increases because the number of carries decreases with decreased collisions
    • C. remains same
    • D. none of the above
      • Discuss
    • 7. In the circuit below, delay of the EXOR and AND


      Logic gates are 20 ?s and 10 ?s respectively, then the wave y' and y (with initial condition y = 1) will be :

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 8. The ratio of the diffusion coefficient in a semiconductor has the units

    • Options
    • A. V-1
    • B. em.V-1
    • C. V.cm-1
    • D. V.s
      • Discuss
    • 9. The amplitude of a pair of composite sinusoidal signal y(n) = x1(n) + x2(n) with x1(n) = sin (5pn) x2(n) = 3 sin (5pn) is __________ .

    • Options
    • A. 2
    • B. 3
    • C. 4
    • D. 1
      • Discuss
    • 10. A TV picture is to be transmitted over a channel of 6 MHz bandwidth at a 35 dB S/N ratio. The capacity of the channel is

    • Options
    • A. 50 Mbps
    • B. 100 Mbps
    • C. 36 Mbps
    • D. 72 Mbps
      • Discuss

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