Term 2 Magnetism and Electromagnetism Three Marks Questions

9th Standard

    Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
    10 x 3 = 30
  1. State an important advantage of ac over dc.

  2. A portable radio has a built in transformer so that if can work from the mains instead of batteries. Is this a step up or step down transformer?

  3. Two coils A and B of insulated wire are kept close to each other. Coil A is connected to a galvanometer. While coil B is connected to a battery through a key. What would happen if
    (i) a current is passed through coil B by plugging the key?
    (ii) the current is stopped by removing the plug from the key?

  4. State Faraday’s laws of electromagnetic induction.

  5. Can two magnetic lines of force intersect? Justify your answer

  6. Give some uses of electromagnets

  7. A conductor of length 50 cm carrying a current of 5 A is placed perpendicular to a magnetic field of induction 2×10-3 T. Find the force on the conductor.

  8. A current carrying conductor of certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, length is halved and magnetic field is tripled?

  9. The primary coil of a transformer has 800 turns and the secondary coil has 8 turns. It is connected to a 220 V ac supply. What will be the output voltage?

  10. A transformer is designed to give a supply of 8 V to ring a house bell from 240 V ac mains. The primary coil has 4800 turns. How many turns will be in the secondary coil.

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