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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.
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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.
संबंधित प्रश्न
Mention various energy losses in transformer device
The primary coil of an ideal step-up transformer has 100 turns and the transformation ratio is also 100. The input voltage and power are 220 V and 1100 W, respectively. Calculate the
(a) number of turns in secondary
(b) current in the primary
(c) a voltage across secondary
(d) current in secondary
(e) power in secondary
The primary coil of a transformed has 800 urns and the secondary coil has 8 turns. It is connected to a 220 V a.c. supply. What will be the output voltage?
Describe the construction and working of a transformer with a neat labelled diagram.
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.
A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns. The number of turns in the secondary in order to get output power at 230 V are ______.
Magnetic flux passing through a coil is initially 4 × 10-4 Wb. It reduces to 10% of its original value in t second. If the emf induced is 0. 72 mV then t in second is ______.
Derive the equation for a transformer.
Explain why core of a transformer is always laminated.
