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प्रश्न
Describe the construction and working of a transformer with a neat labelled diagram.
Explain the working of a transformer with a neat labelled diagram.
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उत्तर
Principle: It is based on the principle of mutual induction, i.e., whenever the magnetic flux linked with a coil changes, an e.m.f is induced in the neighbouring coil.
Construction: A transformer consists of two sets of coils, primary P and secondary S, insulated from each other. Coil P is called the input coil, and coil S is called the output coil. The two coils are wound separately on a laminated soft iron core.
Working: When an alternating voltage is applied to the primary coil, the current through the coil goes on changing. Hence, the magnetic flux through the core also changes. As this changing magnetic flux is linked with both coils, an e.m.f. is induced in each coil. The amount of the magnetic flux linked with the coil depends upon the number of turns of the coil.
Let Φ be the magnetic flux linked per turn with both coils at a certain instant ‘t’. NP and NS be the number of turns of the primary and secondary coils, respectively.
Then at the instant t, the magnetic flux linked with the primary coil ΦP = NPΦ and with the secondary coil ΦS = NSΦ.
The induced emf in the primary and secondary coils will be:
ep = `-(d Phi_p)/(dt) = -N_p(d Phi)/(dt)` ...(1)
es = `-(d Phi_s)/(dt) = -N_s(d Phi)/(dt)` ...(2)
Dividing equation (2) by (1),
∴ `e_s/e_p = N_s/N_p` ...(3)
Equation (3) represents the equation of the transformer.
The ratio `N_s/N_p` is called the turns ratio (transformer ratio) of the transformer.
For an ideal transformer,
Input power = Output power
∴ ePIP = eSIS
∴ `e_s/e_p = I_p/I_s` ....(4)
From equations (3) and (4),
`e_s/e_p = N_s/N_p = I_p/I_s`
Notes
Students should refer to the answer according to their questions.
APPEARS IN
संबंधित प्रश्न
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(A) 600
(B) 500
(C) 400
(D) 300
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Name the phenomenon ?
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Name two kind of energy loss in a transformer. How is it minimized?
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(ii) Explain in brief, its working.
(iii) What material is used for the core of an electric bell? State the reason.
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(iii) Name the type of transformer.
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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, ______.
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.
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The primary coil of a transformer has 60 turns whereas its secondary coil has 3000 turns.
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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?
In an ideal transformer, the turns ratio is `N_p/N_s = 1/2`. The ratio Vs : Vp is equal to (the symbols carry their usual meaning):
