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प्रश्न
Name three losses of energy in a transformer. How are they minimized?
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उत्तर
(i) Heat losses in the windings of transformer. They are minimized by taking a thicker wire in the primary coil than in the secondary coil in a step-up transformer, whereas a thicker wire in secondary coil than in primary coil in a step-down transformer.
(ii) Hysteresis losses in the core of transformer. They are minimized by using soft iron core.
(iii) Eddy current losses in the core of transformer. They are minimized by taking the core laminated instead of taking it as one solid piece.
संबंधित प्रश्न
For what purpose are the transformers used? Can they be used with a direct current source?
Draw a labeled diagram of a full wave rectifier circuit. State its working principle. Show the input-output waveforms ?
Why is the core of a transformer made of soft iron?
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.
Distinguish between Step up and Step Down Transformer.
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, ______.
A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?
Magnetic flux Φ in weber in a closed circuit of resistance 10Ω varies with time Φ (sec) as Φ = 6t2 - 5t + 1. The magnitude of induced current at t = 0.25s is ______.
How do the input and output powers in a transformer compare? State the assumption made.
