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Question
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.
Solution
The working principle of the transformer is the mutual induction. The magnetic flux linked with the primary winding of the transformer must change, to produce an induced emf in the secondary coil.
Transformers cannot work on DC voltages. If a DC supply is given to the primary coil of a transformer, it produces a steady magnetic flux. So, no emf will be induced in the secondary coil.
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RELATED QUESTIONS
A group of students while coming from the school noticed a box marked "Danger H.T. 2200 V" at a substation in the main street. They did not understand the utility of a such a high voltage, while they argued, the supply was only 220 V. They asked their teacher this question the next day. The teacher thought it to be an important question and therefore explained to the whole class.
Answer the following questions:
(i) What device is used to bring the high voltage down to low voltage of a.c. current and what is the principle of its working ?
(ii) Is it possible to use this device for bringing down the high dc voltage to the low voltage? Explain
(iii) Write the values displayed by the students and the teacher.
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(A) 600
(B) 500
(C) 400
(D) 300
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Long distance power transmissions
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