Induced voltage and inductance, Electrical Engineering

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

 

Posted Date: 8/22/2012 5:32:52 AM | Location : United States







Related Discussions:- Induced voltage and inductance, Assignment Help, Ask Question on Induced voltage and inductance, Get Answer, Expert's Help, Induced voltage and inductance Discussions

Write discussion on Induced voltage and inductance
Your posts are moderated
Related Questions
Use Norton Theorem, find the current flow through resistor R=10Ω.

Speed control of DC Motor The DC  motor  are versatile motors among the  available  electrical  motors due to  their  superior  characteristics. These motors  give a smooth sp

How to Make LPG Safer in the Laboratory The following must be observed in the laboratory: 1. The LPG cylinders should be kept outside the laboratory in a ventilated room.


Solve using data from the DC machine data sheet, using the "hot" resistance value for all calculations. Note that the value of K on the sheet is for rated (100%) field flux. Assum

Define The universal property of NAND and NOR Gates? The NAND and NOR gates are called universal gates, because any gate can build by using these two gates. The univers

Q. The effective area of a dipole is given by A e =0.13λ 2 . Find the effective area of a half-wave dipole at 3 GHz.

Explain the effect of temperature on electrical conductivity of metals. As the temperature is increased, there is a greater thermal motion of atoms which decreases the regulari

does wein bridge can be used for frequency measurement? how it is possible?

When a current is passed through a conductor, a magnetic field is created in its surroundings. We can represent this magnetic field by drawing 'field (or 'flux') lines' with two