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General Knowledge :: Physics

  1. Which sources produce alternating current (AC)?

  2. A.

     Solar power plants

    B.

     Hydro-electric generators

    C.

     Batteries

    D.

     All of the above


  3. Alternating current is converted into direct current by a

  4. A.

     Transformer

    B.

     Dynamo

    C.

     Oscillator

    D.

     Rectifier


  5. Speed regulation of synchronous motor is

  6. A.

     1%

    B.

     25%

    C.

     Zero

    D.

     0.5%


  7. A parallel-plate capacitor,with air in between the plates, has capacitance C. Now the space between the two plates of the capacitor is filled with a dielectric of dielectric constant 7. Then the value of the capacitance will become

  8. A.

     C

    B.

     C/7

    C.

     7C

    D.

     14C


  9. A parallel-plate capacitor of capacitance C1 is made using two gold plates. Another parallel-plate capacitor of capacitance C2 is made using two aluminium plates with same plate separation, and all the four plates are of same area. If rg and ra are respectively the electrical resistivities of gold and aluminium, then which one of the following relations is correct?

  10. A.

     C1>C2

    B.

     C2>C1

    C.

     C1pa = C2pg

    D.

     C1 = C2


  11. Which compressor is usually used in AC?

  12. A.

     Centrifugal

    B.

     Rotary

    C.

     Reciprocating

    D.

     Axial


  13. The best material for the core of a transformer is

  14. A.

     Stainless steel

    B.

     Mild steel

    C.

     Hard steel

    D.

     Soft iron


  15. A transformer works on the principle of

  16. A.

     Self induction

    B.

     Mutual induction

    C.

     Generator

    D.

     Inverter


  17. Transformer is a device to convert

  18. A.

     D.C. to A.C.

    B.

     Low voltage D.C. into high voltage D.C.

    C.

     Low voltage A.C. into high voltage A.C.

    D.

     Mechanical energy into Electrical energy


  19. Atomic hydrogen has a life period of

  20. A.

     One hour

    B.

     One day

    C.

     One minute

    D.

     A fraction of a second