logo

CuriousTab

CuriousTab

Discussion


Home Electronics and Communication Engineering Materials and Components Comments

  • Question
  • The temperature coefficient of resistivity of semiconductors is


  • Options
  • A. positive
  • B. negative
  • C. may be positive or negative
  • D. very low

  • Correct Answer
  • negative 

    Explanation
    Resistance of semiconductors decreases with increase in temperature.

    Materials and Components problems


    Search Results


    • 1. A good dielectric should have

    • Options
    • A. low losses
    • B. good heat conductivity
    • C. high intrinsic strength
    • D. all of the above
    • Discuss
    • 2. Assertion (A): In an intrinsic semiconductor J = (?n x ?p)eni.

      Reason (R): Intrinsic charge concentration ni at temperature T is given by ni2 = A0 T3 e-EG0/kT.


    • Options
    • A. Both A and R are true and R is correct explanation of A
    • B. Both A and R are true but R is not correct explanation of A
    • C. A is true but R is false
    • D. A is false but R is true
    • Discuss
    • 3. A parallel plate capacitor has area of plate A and plate separation d. Its capacitance is C. A metallic plate P of area A and negligible thickness is added as shown in Figure. The new value of capacitance is

    • Options
    • A. C
    • B. 2C
    • C. 0.5 C
    • D. 0.25 C
    • Discuss
    • 4. A copper atom is neutral. Its core has a net charge of

    • Options
    • A. 0
    • B. + 1
    • C. - 1
    • D. + 2
    • Discuss
    • 5. Assertion (A): In ionic dielectrics, P = Pe + Pi.

      Reason (R): In ionic crystals, permanent electric dipole moment is zero.


    • Options
    • A. Both A and R are true and R is correct explanation of A
    • B. Both A and R are true but R is not correct explanation of A
    • C. A is true but R is false
    • D. A is false but R is true
    • Discuss
    • 6. Which of these has the highest dielectric strength?

    • Options
    • A. Mica
    • B. Air
    • C. Cotton
    • D. Rubber
    • Discuss
    • 7. When a dielectric is subjected to an electric field E, each volume element of dielectric can be considered to be carrying an electric dipole moment.

    • Options
    • A. True
    • B. False
    • Discuss
    • 8. Assertion (A): Doping level in extrinsic semiconductors is very small.

      Reason (R): Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20.


    • Options
    • A. Both A and R are true and R is correct explanation of A
    • B. Both A and R are true but R is not correct explanation of A
    • C. A is true but R is false
    • D. A is false but R is true
    • Discuss
    • 9. Which of the following is used in automatic control of street lights?

    • Options
    • A. Thermistor
    • B. Photoconductor
    • C. Transistor
    • D. Varistor
    • Discuss
    • 10. A leaky dielectric has ?r = ?r' - j?r". If a field E is applied, the current component in phase with E is proportional to ?r".

    • Options
    • A. True
    • B. False
    • Discuss


    Comments

    There are no comments.

Enter a new Comment