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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
Express the turn ratio in terms of voltages.
Which coil of a step up transformer is made thicker and why?
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.
Explain why an induced current must flow in such a direction so as to oppose the change producing it.
Why is the iron core of a transformer made laminated (thin sheets) instead of being in one solid piece?
What is the function of a step-up transformer?
A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?
Read the following paragraph and answer the question:
Long distance power transmissions
The large-scale transmission and distribution of electrical energy over long distances is done with the use of transformers. The voltage output of the generator is stepped up. It is then transmitted over long distances to an area sub-station near the consumers. There the voltage is stepped down. It is further stepped down at distributing sub-stations and utility poles before a power supply of 240 V reaches our homes.
If the secondary coil has a greater number of turns than the primary, ______.
The line that draws power supply to your house from street has ______.
- zero average current.
- 220 V average voltage.
- voltage and current out of phase by 90°.
- voltage and current possibly differing in phase `phi` such that `|phi| < pi/2`.
