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प्रश्न
State the principle of a transformer.
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उत्तर
It is based on the principle of ‘electromagnetic induction’. The magnitude of induced e.m.f. is given by the formula.
`"No. of turns in primary coil"/"No.of. turns in secondary coil" = "E.m.f. in primary"/"E.m.f in secondary"`
Neglecting power losses
Elective power fed in the primary (input) = Elective power produced in secondary (output)
or Ep × iP = Es × is
`"E"_"p"/"E"_"s" = "i"_"s"/"i"_"p"`
संबंधित प्रश्न
Name two factors on which the magnitude of an induced e.m.f. in the secondary coil depends.
The teachers of Geeta’s school took the students on a study trip to a power generating station, located nearly 200 km away from the city. The teacher explained that electrical energy is transmitted over such a long distance to their city, in the form of alternating current (ac) raised to a high voltage. At the receiving end in the city, the voltage is reduced to operate the devices. As a result, the power loss is reduced. Geeta listened to the teacher and asked questions about how the ac is converted to a higher or lower voltage.
1) Name the device used to change the alternating voltage to a higher or lower value. State one cause for power dissipation in this device.
2) Explain with an example, how power loss is reduced if the energy is transmitted over long distances as an alternating current rather than a direct current.
3) Write two values each shown by the teachers and Geeta.
The adjacent diagram shows a coil would around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way increasing the strength of electromagnet so formed.
Name two kind of energy loss in a transformer. How is it minimized?
Describe briefly and two energy losses, giving the reasons for their occurrence in actual transformers ?
Name three losses of energy in a transformer. How are they minimized?
State whether true or false. If false, correct the statement.
A transformer can step up direct current.
Mention the various energy losses in a transformer.
In an ideal transformer, the turns ratio is \[\frac {N_p}{N_s}\] = \[\frac {1}{2}\]. The ratio Vs : Vp is equal to (the symbols carry their usual meaning) ______.
