Induced voltage and inductance, Electrical Engineering

Assignment Help:

Experiments conducted by Faraday and others using current carrying coils resulted in 'The Laws of Electromagnetic Induction' which state:

1)  'If the magnetic flux threading through an electrical circuit changes, then an e.m.f. is induced in the circuit'.
 
2) 'The magnitude of the induced e.m.f. is proportional to the rate of change of the magnetic  flux  through the     circuit'. (Faraday's Law)

3) 'The induced e.m.f. has a direction such that  the  current  which  flows  (or  would flow if the circuit is completed) gives rise to magnetic effects that oppose the effects producing it'.(Lenz's Law)

 

These principle are widely used to convert mechanical power into electrical power - e.g the alternator.These are general principles that are true however the change in flux is produced. It may be due to:

 

  •  moving magnets near the coil
  •  changing the current  flowing  in a nearby coil
  •  changing the current within the coil itself
  •  relative movement between the coil and the magnetic field.

The polarity of the emf produced will act to try to oppose the change causing it. If it is due to an external flux change, the induced emf will drive a current in the coil that itself produces a flux that opposes the change due to the external influence.

If the flux change is due to a change in the current within the coil, the emf generated will act to oppose the change in current. This is called a 'back emf'.
 
Faraday was able to quantify the effect and expressed the observations mathematically as:

v=-Ndq/dt   (Faraday's Law)

 where N is the number of turns on the coil and dq/dt  is the rate of change of flux threading the coil. Effectively, each turn  generates a back emf equal to dq/dt  and since the emfs produced by each turn are in  series, the total back emf is N times that of
each turn considered separately

 


Related Discussions:- Induced voltage and inductance

Why earthing is required for any electrical equipments, Why earthing is req...

Why earthing is required for any electrical equipments, domestic installation and service building etc? For TL coaches what is the minimum I.R. value needed for new wiring? An

Simple zener voltage regulator, Consider a simple zener voltage regulator w...

Consider a simple zener voltage regulator with the circuit diagram shown in Figure (a). (a) For a small reverse resistance R Z S and V S - R S i out > V Z , show that v ou

Why fet is called a voltage-controlled device, Q. Why FET is called a volta...

Q. Why FET is called a voltage-controlled device? Why its input resistance is high? In the case of a FET the output current ID is a function of the voltage VGS applied to the i

Explain light-emitting diode, Q. Explain Light-emitting diode? This is ...

Q. Explain Light-emitting diode? This is a reliable, rugged, and inexpensive semiconductor display device requiring about 10 mA of current flow for full illumination. An LED is

Averaged power dissipated in the load, (a) Consider the following transmiss...

(a) Consider the following transmission line with the reactance X1 placed across the input. It is being driven with a frequency ω such that the length of the line is λ/4. What v

Find the resistance of wire, The resistance of a wire is 60 ? at 25 o C and...

The resistance of a wire is 60 ? at 25 o C and 65? at 75 o C. Find the resistance of wire at 0 o C and value of temperature co-efficient at 0 o C. Ans: Given R 25 = 60 ? a

Different types and uses of delay line in cro, Q.   What are the different ...

Q.   What are the different types and uses of delay line in CRO? OR Why is a delay line used in the vertical section of the oscilloscope? Sol. All electronic circui

What is the significance of source gate cutoff voltage, Q. What is the sign...

Q. What is the significance of source gate cutoff voltage? The source gate cutoff voltage is also called pinch off voltage. It is obtained when VDS increases and approaches a l

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd