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Explain step up and step down transformer?

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प्रश्न

Explain step up and step down transformer?

थोडक्यात उत्तर
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उत्तर

  1. Step-up transformer:
    a.
    A transformer that converts a low voltage at high current into a high voltage at low current is called a step-up transformer.
    b. In a step-up transformer, the number of turns in secondary coil NS is greater than the number of turns in primary coil NP. In this transformer, eS > eP and IS < IP.  
    c. The primary coil is made from a thick insulated copper wire so that it can sustain the high current. The secondary coil is made of a thin insulated wire.
    d. Current through secondary is less than primary. 
  2. Step down transformer:
    a. A transformer which converts a high voltage at low current into a low voltage at high current is called a step-down transformer.
    b. In step down transformer, the number of turns in the secondary coil NS is less than the number of turns in the primary coil NP. In this transformer eS < eP and IS > IP.
    c. The primary coil is made of a thin insulated wire and the secondary coil is made from thick wire so that it can sustain the high current.  
    d. Current through primary is less than secondary. 
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पाठ 12: Electromagnetic Induction - Short Answer II

व्हिडिओ ट्यूटोरियलVIEW ALL [3]

संबंधित प्रश्‍न

Explain the construction and working of the transformer. 


Derive an expression for ratio of e.m.f.s and currents in terms of number of turns in primary and secondary coil.


Find the ratio of primary and secondary currents in terms of turn ratio in an ideal transformer.


How much current is drawn by the primary of a transformer connected to 220 V supply when it delivers power to a 110 V − 550 W refrigerator?


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


Name two factors on which the magnitude of an induced e.m.f. in the secondary coil depends.


Explain the significance of Lenz’s law to show the conservation of energy in electromagnetic induction.


How are the e.m.f in the primary and secondary coils of a transformer related with the number of turns in these coils?


The secondary windings of a transformer in which the voltage is stepped down are usually made of thicker wire than the primary. Explain why.


The transformer is used in ______ current circuits.


Name two kind of energy loss in a transformer. How is it minimized?


The primary coil of a transformed has 800 urns and the secondary coil has 8 turns. It is connected to a 220 V a.c. supply. What will be the output voltage?


A transformer is designed to work from a 240 V a.c. mains and to give a supply of 8 V to ring a house bell. The primary coil has 4800 turns. How many turns will be in the secondary coil?


The input and output voltage of a transformer are 220 V and 44 V respectively. Find:  the turns ratio.


Describe briefly, with the help of labelled diagram, working of a step-up transformer.

A step-up transformer converts a low voltage into high voltage. Does it not violate the principle of conservation of energy? Explain.


What is the turns ratio i.e., transformer ratio, ns: np, in an ideal transformer which in-creases ac voltage from 220 V to 33000 V?


What is a transformer? On what principle does it work?


Can a transformer be used with direct current source? Give reason.


State the factors on which the frequency of the alternating e.m.f. depends.


Name the principle on which functioning of a transformer depends.


Draw a labelled diagram to show the various parts of a step-up transformer and step down transformer.


A transformer lowers e.m.f. from 220 V to 15 V. If 400 W power is given in primary, calculate (i) the current in primary coil and (ii) the current in secondary coil.


A circular coil of 100 turns with a cross-sectional area of 1 m2 is kept with its plane perpendicular to the magnetic field of 1 T. The magnetic flux linkage is ______.


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 ______ 


Explain the working of the transformer.


A step-down transformer connected to the main supply of 220 V is used to operate 11V,88W lamp. Calculate

  1. Voltage transformation ratio and
  2. Current in the primary

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 ____________.


A transformer is based on the principle of ______.

Eddy currents in the core of transformer can't be developed by ______.

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?


A transformer is essentially an a.c. device. It cannot work on d.c. It changes alternating voltages or currents. It does not affect the frequency of a.c. It is based on the phenomenon of mutual induction. A transformer essentially consists of two coils of insulated copper wire having different numbers of turns and wound on the same soft iron core.

The number of turns in the primary and secondary coils of an ideal transformer is 2000 and 50 respectively. The primary coil is connected to a main supply of 120 V and secondary coil is connected to a bulb of resistance 0.6 Ω.

The value of voltage across the secondary coil is ______.


Define a Transformer.


A transformer is used ______


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 ______.


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.


What is a transformer?


What type of transformer is used in a mobile phone charger?


In an ideal transformer, the turns ratio is \[\frac {N_p}{N_s}\] = \[\frac {1}{2}\]. The ratio Vs : Vp is equal to (the symbols carry their usual meaning) ______.


On which principle is a transformer based?


How is the laminated soft iron core made?


Which description of the primary coil is correct?


Which winding is the output coil connected to the load?


Which description of the secondary coil is correct?


Where is alternating voltage \[V_p\] applied?


Which law relates the changing flux to the EMF induced in both coils?


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