Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
For the simple transformer shown in the figure, the output voltage VS depends almost entirely on the input voltage VP and the ratio of the number of loops in the primary and secondary coils. Faraday's law of induction for the secondary coil gives its induced output voltage VS to be
`V_S = -N_S((Deltaphi)/(Deltat))` .....(i)
Where NS is the number of loops in the secondary coil and `(Deltaphi)/(Deltat)` is the rate of change of magnetic flux.
The cross-section area of the coils is the same on either side, as is the magnetic field strength, and so `(Deltaphi)/(Deltat)` is the same on either side. The input primary voltage VP is also related to changing flux by
`V_P = -N_P(Deltaphi)/(Deltat)` .....(ii)
Lenz's law tells us that the primary coil opposes the change in flux caused by the input voltage VP hence the minus sign is given.
Dividing both the equation, we get
`V_S/V_P = N_S/N_P`
`V_S = V_P(N_S/N_P)`
APPEARS IN
संबंधित प्रश्न
Explain why an induced current must flow in such a direction so as to oppose the change producing it.
How are the e.m.f in the primary and secondary coils of a transformer related with the number of turns in these coils?
What is a transformer? On what principle does it work?
Name the principle on which functioning of a transformer depends.
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 voltage across the secondary coil 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.
The value of current in primary coil is ______.
Define a Transformer.
Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?
- For a given power level, there is a lower current.
- Lower current implies less power loss.
- Transmission lines can be made thinner.
- It is easy to reduce the voltage at the receiving end using step-down transformers.
A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10 A, then the input voltage and current in the primary coil are ______.
