English

Distinguish between Step up and Step Down Transformer. - Physics

Advertisements
Advertisements

Question

Distinguish between Step up and Step Down Transformer.

Distinguish Between
Advertisements

Solution

No. Step-up transformer Step-down transformer
i. The number of turns in its secondary is more than that in its primary (NS > NP). The number of turns in primary is greater than in secondary (NP > NS). 
ii. The alternating voltage across the ends of its secondary is more than that across its primary, i.e., eS > eP. The alternating voltage across the ends of the primary is more than that across its secondary, i.e., eP > eS.
iii. Transformer ratio K > 1. Transformer ratio K < 1.
iv. Primary coil made of thick wire. Secondary coil made of thick wire.
v. The secondary coil is made of thin wire. The primary coil is made of thin wire. 
vi. Current through secondary is less than primary. Current through primary is less than secondary.
shaalaa.com
  Is there an error in this question or solution?
Chapter 12: Electromagnetic Induction - Short Answer I

APPEARS IN

SCERT Maharashtra Physics [English] 12 Standard HSC
Chapter 12 Electromagnetic Induction
Short Answer I | Q 7

RELATED QUESTIONS

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 the step-down transformer and its working.


Express the turn ratio in terms of voltages.


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


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


Which coil of a step up transformer is made thicker and why?


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


Complete the following sentence :
……… energy is converted into …………energy by an electric motor.


State two factors on which the magnitude of induced e.m.f. depend.


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.


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


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?


Given the input current 15 A and the input voltage of 100 V for a step-up transformer having 90% efficiency, find the output power and the voltage in the secondary if the output current is 3 A.  


Mention the two characteristic properties of the material suitable for making core of a transformer.


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.


An a.c generator generates an emf 'ε' where ε = 314 Sin (50πt) volt. Calculate the frequency of emf ε.


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


Name the principle on which functioning of a transformer depends.


Why is the core of a transformer made of soft iron?


(i) Draw a clear labelled diagram of an electric bell.
(ii) Explain in brief, its working.
(iii) What material is used for the core of an electric bell? State the reason.


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.


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.


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 ______ 


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.


State whether true or false. If false, correct the statement.

A transformer can step up direct current.


A step-down transformer reduces the supply voltage from 220 V to 11 V and increase the current from 6 A to 100 A. Then its efficiency is


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%


A step-up transformer has 300 turns of primary winding and 450 turns of secondary winding. A primary is connected to 150 V and the current flowing through it is 9A. The current and voltage in the secondary are 


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

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


A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?


The core of transformer is laminated to reduce ______.

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

A transformer is employed to ______.

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.

A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns. The number of turns in the secondary in order to get output power at 230 V are ______.


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 primary coil is ______.


Name one electrical device which works on Faraday's law of electromagnetic induction principle.


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


Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?

  1. For a given power level, there is a lower current.
  2. Lower current implies less power loss.
  3. Transmission lines can be made thinner.
  4. It is easy to reduce the voltage at the receiving end using step-down transformers.

For an LCR circuit, the power transferred from the driving source to the driven oscillator is P = I2Z cos φ.

  1. Here, the power factor cos φ ≥ 0, P ≥ 0.
  2. The driving force can give no energy to the oscillator (P = 0) in some cases.
  3. The driving force cannot syphon out (P < 0) the energy out of oscillator.
  4. The driving force can take away energy out of the oscillator.

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


A 60 W load is connected to the secondary of a transformer whose primary draws line voltage. If a current of 0.54 A flows in the load, what is the current in the primary coil? Comment on the type of transformer being used.


1 MW power is to be delivered from a power station to a town 10 km away. One uses a pair of Cu wires of radius 0.5 cm for this purpose. Calculate the fraction of ohmic losses to power transmitted if

  1. power is transmitted at 220 V. Comment on the feasibility of doing this.
  2. a step-up transformer is used to boost the voltage to 11000 V, power transmitted, then a step-down transfomer is used to bring voltage to 220 V. (ρCu = 1.7 × 10–8 SI unit)

An iron rod is placed parallel to magnetic field of intensity 2000 Am-1. The magnetic flux through the rod is 6 × 10−4 Wb and its cross-sectional area is 3 cm2. The magnetic permeability of the rod in Wb A-1m-1 is ______.


Magnetic flux passing through a coil is initially 4 × 10-4 Wb. It reduces to 10% of its original value in t second. If the emf induced is 0. 72 mV then t in second is ______.


An iron rod of 0.2 cm2 cross-sectional area is subjected to a magnetising field of 1200 Am-1. If the susceptibility of iron is 599, then the magnetic flux produced is ______.


The primary coil having NP turns of an ideal transformer is supplied with an alternating voltage VP. Obtain an expression for the voltage VS induced in its secondary coil having NS turns.


Derive the equation for a transformer.


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


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×