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
Specific orientation programme: at this stage, induction is conducted by the foreman. Induction is specific and requires skill on the part of the foreman. A new employee must be p

a) Write down a short note on compensators. b) Classify filter with relevant sketches. c) Illustrate the principle and working of Analog to Digital converter.

Mesh analysis procedure : 1.  Assign a distinct current to every closed loop of the network. 2.  Apply KVL around every closed loop of the network. 3.  Solve the resulting

jsidjsiod dkndkdisd dknssbs bsjbabd asj u dhihf ujojdsajfs sjssaidhsidw idgsdusadidjwap ewkeowr krwnrh bwvr [ wrj wrj 1 nnwoi khiwrjw ko e woewerijr rjwr jr rjhpr

A capacitor is charged to 100 V and then discharged by a 50 kΩ resistor. If the time constant of the circuit is 0.8 s, verify: (a)  The value of the capacitor, (b)  The time

Relays a) Sketch the schematic symbol for a relay with a single pole changeover switch b) Determine the coil resistance and determine the current at 12Vdc c) Connect the r

A four-pole, three-phase, wound-rotor induction machine is to be used as a variable-frequency supply. The frequency of the supply connected to the stator is 60 Hz. (a) Let the r

Calculate the maximum length of an optical fibre that exhibits 0.8dB/km attenuation if the optical output is 10mW and the power launched at the input is 150mW. [Hint: Loss, L=10 lo

The creation of a magnetic field in a ring may need to be accessed by means of an air gap. This is typically used to apply the magnetic field to a current carrying conductor to pro

Q. Compare electromechanical switching system with electronic switching system. Sr. No Electromechanical switching System Electroni