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प्रश्न
The power supply to the primary coil of a transformer is 200 W. Find
(i) Current in primary coil if the e.m.f. supply to it is equal to 220V.
(ii) The number of turns in the primary coil is equal to 80 and that in secondary is 800. What is the transformation ratio?
(iii) Name the type of transformer.
(iv) What will be the output voltage?
(v) What is the current in the secondary coil for an ideal transformer?
(vi) What is the output power?
(vii) Is output and input power equal?
(viii) Compare the current flowing in a secondary coil and in a primary coil.
उत्तर
(i) P(Power) = 200W = VI = Ep × Ip
∴ P = 200 = 200 × Ip
∴ Current in the primary coil = `200/220`
Ip = 0.909 A
(ii)
Transformation ratio `"E"_"s"/"E"_"p" = "N"_"s"/"N"_"p" = 800/80 = 10`
(iii) It is a step up transformer.
(iv) Using `"E"_"s"/"E"_"p" = "N"_"s"/"N"_"p" = 10`
` therefore "E"_"s"/200 = 10`
∴ Es = 2200 V
(v) Using Ep × Ip = 2200 × Is
∴ 200 = 2200 × Is
∴ Is = `2/22 = 0.090` A
(vi) Outpput power = Es × Is = `(2200 xx 0.0909)/100 = 200`W
(vii) Yes, It is equal, because it is an ideal transformer, for an ideal transformer
Efficiency = η = `"Outout power"/"Input power" = 1 "or" 100%`
i.e., there is no energy loss due to any cause.
(viii) Is = 0.0909 A and Ip = 0.909 A
Less current flows through the secondary coil than in the primary coil because it is a step-up transformer.
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संबंधित प्रश्न
Draw a labeled diagram of a step-down transformer.
On which type of current do transformers work?
State the principle of working of a transformer. Can a transformer be used to step up or step down a d.c. voltage? Justify your answer.
Describe briefly, with the help of labelled diagram, working of a step-up transformer.
A step-up transformer converts a low voltage into high voltage. Does it not violate the principle of conservation of energy? Explain.
Assertion: A transfonner cannot work on D.C. supply.
Reason: D.C. changes neither in magnitude nor in direction.
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.
Which of the following statement is true?
The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an a.c supply of 120 V and the current flowing in its is 10 A. The voltage and the current in the secondary are ______.
The primary coil of a transformer has 60 turns whereas its secondary coil has 3000 turns.
If a current of 5A flows in the primary coil, how much current will flow in a load in the secondary coil? State the assumption you have made regarding the transformer, in this calculation.
