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Question
State the principle on which transformer works.
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Solution
A transformer is a device with the help of which, a given alternating voltage can be increased or decreased to any desired value. The first type of transformer which delivers an output voltage smaller than the input voltage
is called a step down transformer. The second type of transformer which delivers an output voltage larger than the input voltage is called a step up transformer.
Principle of working of a transformer:
A transformer works on the principle that whenever the magnetic flux linked with a coil changes, an emf is induced in the neighbouring coil.
RELATED QUESTIONS
Explain the construction and working of the transformer.
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
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A step-up transformer converts a low voltage into high voltage. Does it not violate the principle of conservation of energy? Explain.
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.
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State the principle of a transformer.
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The power supply to the primary coil of a transformer is 200 W. Find
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(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.
The primary coil of a transformer has 200 turns while the secondary coil has 1000 turns. What type of transformer is this? if the input voltage is 10V, what will be the output voltage?
Applying e.m. f to primary coil is 210 V. If the number of turns in primary coil is 200 turns and that of in secondary coil is 20 turns, then find out the output voltage. Name the type of transformer.
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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 ______
Distinguish between Step up and Step Down Transformer.
The primary of a transformer has 40 turns and works on 100 V and 100 W. Find a number of turns in the secondary to step up the voltage to 400 V. Also calculate the current in the secondary and primary.
The 300 turn primary of a transformer has resistance 0.82 Ω and the resistance of its secondary of 1200 turns is 6.2 Ω. Find the voltage across the primary if the power output from the secondary at 1600V is 32 kW. Calculate the power losses in both coils when the transformer efficiency is 80%
A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the ratio of output to input power is 0.8, then the current drawn by primary winding is ______.
A transformer having efficiency of 80% is working on 200 V and 6 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are ____________.
For an ideal step-down transformer, the quantity which is constant for both the coils is ______.
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.
Which of the following statement is true?
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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For an LCR circuit, the power transferred from the driving source to the driven oscillator is P = I2Z cos φ.
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- The driving force cannot syphon out (P < 0) the energy out of oscillator.
- The driving force can take away energy out of the oscillator.
The magnetic flux through a coil perpendicular to its plane is varying according to the relation Φ = (5t3 + 4t2 + 2t - 5) Weber. If the resistant of the coil is 5 ohm, then the induced current through the coil at t = 2 sec will be ______.
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Efficiency of transformer is the ratio of ______.
The self-inductance of a closely wound coil of 200 turns is 10 mH. Determine the value of magnetic flux through the cross-section of the coil when the current passing through the coil is 4 mA.
The primary coil of a transformer has 60 turns whereas its secondary coil has 3000 turns.
If a 220 V ac voltage is applied to the primary coil, how much emf is induced in the secondary coil?
The primary coil of a transformer has 60 turns whereas its secondary coil has 3000 turns.
If a current of 5A flows in the primary coil, how much current will flow in a load in the secondary coil? State the assumption you have made regarding the transformer, in this calculation.
What is a transformer?
What type of transformer is used in a mobile phone charger?
Explain why core of a transformer is always laminated.
For what purpose are the transformers used?
A 12 V, 60 W lamp is connected to 220 V AC via an ideal transformer. Find the primary current.
