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प्रश्न
State the principle of the step-down transformer and its working.
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उत्तर
Principle: A transformer is based on the principle of electromagnetic mutual induction, i.e., whenever the amount of magnetic flux linked with a coil changes, an e.m.f. is induced in the neighboring coil.
Working
Alternating emf is supplied to the primary coil PP’. The resulting current induces a current in the secondary coil.
Magnetic flux linked with primary is also linked with the secondary. The induced emf in each turn of the secondary is equal to that induced in each turn of the primary.
Let
EP − Alternating emf applied to primary
nP − Number of turns in the primary
`(dphi)/dt-"Rate of change of flux through each turn of primary coil"`
`:.E_p=-n_p (dphi)/dt" ......(1)"`
Es− Alternating emf of secondary
ns − Number of turns in secondary
`:.E_s=-n_s (dphi)/dt" ....(2)"`
Dividing equation (2) by (1),
`E_s/E_p=n_s/n_p=k`
For step-up transformer, K > 1
∴ Es > Ep
For step-down transformer, K < 1
∴ Es < Ep
APPEARS IN
संबंधित प्रश्न
Draw a labeled diagram of a step-down transformer.
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.
Describe, with the help of a suitable diagram, the working principle of a step-up transformer. Obtain the relation between input and output voltages in terms of the number of turns of primary and secondary windings and the currents in the input and output circuits.
State the principle of a step-up transformer. Explain, with the help of a labeled diagram, its working ?
A transformer is used to step up an alternating emf of 200V to 440V. If the primary coil has 1000 turns, calculate the number of turns in the secondary coil.
Can a transformer be used with direct current source? Give reason.
The primary and secondary coils of a transformer each have an inductance of 200 x 10-6 H. The mutual inductance between the windings is 4 x 10-6 H. What percentage of the flux from one coil reaches the other?
An ideal transformer has 100 turns in the primary and 250 turns in the secondary. The peak value of the AC is 28 V. The rms secondary voltage is nearest to ______
Define a Transformer.
Efficiency of transformer is the ratio of ______.
