मराठी
महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Explain step up and step down transformer? - Physics

Advertisements
Advertisements

प्रश्न

Explain step up and step down transformer?

थोडक्यात उत्तर
Advertisements

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. 
shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 12: Electromagnetic Induction - Short Answer II

व्हिडिओ ट्यूटोरियलVIEW ALL [3]

संबंधित प्रश्‍न

Derive an expression for e.m.f. and current in terms of turns ratio


A power transmission line feeds input power at 2200 V to a step-down transformer with its primary windings having 300 turns. Find the number of turns in the secondary to get the power output at 220 V.


State the principle of transformer working with the help of a diagram


Name the transformer used in the power transmitting station of a power plant.


You are required to make an electromagnet from a soft iron bar by using a cell, an insulated coil of copper wire and a switch. (a) Draw a circuit diagram to represent the process. (b) label the poles of the electromagnet.


The adjacent diagram shows a coil would around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way increasing the strength of electromagnet so formed.


Name the phenomenon ?


The following diagram in Fig. 10.44 shows a coil X connected to a sensitive centre –zero galvanometer G and a coil P connected to a battery through a switch S.

(a) Describe the observation when the switch S is (i) closed suddenly, (ii) then kept closed, (iii) finally opened.
(b) Name and state the law which explains the above observations.


Why is the iron core of a transformer made laminated (thin sheets) instead of being in one solid piece?


The transformer is used in ______ current circuits.


In a transformer, the frequency of A.C. 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?


State the principle of a step-up transformer. Explain, with the help of a labeled diagram, its working ?


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.


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. 


The input and output voltages of a transformer are 220 V and 44V respectively. Find the current in input circuit if the output current is 2 A.


What is the ideal transformer? 


State the principle of a transformer.


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


The power supply to the primary coil of a transformer is 200 W. Find
(i) Current in primary coil if the e.m.f. supply to it is equal to 220V.
(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.


A transformer lowers e.m.f. from 220 V to 15 V. If the number of turns in primary are 3520, how many turns are in the secondary coil?


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?


State the mathematical relation between a number of turns in the primary coil to a secondary coil in the step-up transformer. 


Distinguish between Step up and Step Down Transformer.


What is Transformer?


Describe the construction and working of a transformer with a neat labelled diagram.


In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is


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 200V/120V step-down transformer of 90% efficiency is connected to an induction stove of resistance 40 Ω. Find the current drawn by the primary of the transformer.


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%


Assertion: A transfonner cannot work on D.C. supply.

Reason: D.C. changes neither in magnitude nor in direction.


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 100% efficient transformer has 100 turns in the primary and 50 turns in its secondary coil. If the current in the secondary coil is 6 A, then the current in the primary coil is ______.


A transformer is based on the principle of ______.

The transformation ratio in the step-up transformer is ______.

A transformer is employed to ______.

A transformer works on the principle of ______.


For an ideal step-down transformer, the quantity which is constant for both the coils is ______.


Which among the following, is not a cause for power loss in a transformer?


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.

We need to step-up the voltage for power transmission, so that ______.


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 current in the bulb is ______.


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.

Power in primary coil is ______.


Define a Transformer.


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?


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?


Draw the effective equivalent circuit of the circuit shown in figure, at very high frequencies and find the effective impedance.


Magnetic flux Φ in weber in a closed circuit of resistance 10Ω varies with time Φ (sec) as Φ = 6t2 - 5t + 1. The magnitude of induced current at t = 0.25s is ______.


The large scale transmission of electrical energy over long distances is done with the use of transformers. The voltage output of the generator is stepped-up because of ______.


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.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×