A.C.Circuits

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Hey someone post some quality notes on the following topics:
1. Special cases for RL and RC circuits
2. Phasor diagrams
3. Oscillations in an LC Circuit
4. Measurement of fringe width using a telescope

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LC Oscillations

Capacitors and inductors are capable of storing energy in the electric field and magnetic field respectively.
No A.C elements i.e., capacitor, inductor are pure. In other words each of them do have some resistance. The charges or current through these elements lose their energy as heat due to the resistance. The energy is radiated away in form of electromagnetic wave, which is the basis of radio, T.V transmission. As the circuits give away this energy, this loss has to be replenished. This is done using a L.C circuit. Consider the circuit below:
A.C.Circuits L-c-circuit

The capacitor, which charged, is connected to the indicator. The capacitor starts discharging i.e., the charges on capacitor start decreasing. If q and I were the charge and current then according to Kirchoff's Law.
A.C.Circuits Img82

(i.e., e.m.f across C = e.m.f across L)
The solution for the above equation being
A.C.Circuits Img83

i.e, the charge and hence current is oscillatory. This means its magnitude and direction keeps changing. The charge on the capacitors going through the inductor generates a magnetic field and thereby some energy is stored in the magnetic field. The current slowly reaches a maximum when the capacitor is fully discharged. The induced current in the inductor opposes this and charges the capacitor in opposite direction.
A.C.Circuits Charged-capacitor-indicator

A.C.Circuits Charged-capacitor-indicator

The whole process repeats once again. The energy of system oscillates between capacitor and the inductor.

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RC Circuit

Phasor Diagram:
A.C.Circuits Rcimp5

I = Current
Z = Impedance
A.C.Circuits Rcimp

RL Circuit

Phasor Diagram:
A.C.Circuits Rlimp5

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Derivations are given clearly in S.Chand.. It is the simplest..! A.C.Circuits Icon_biggrin

Subject: Re: A.C.Circuits Tue Mar 09, 2010 4:17 pm

tas true winRrule i believe S.Chand is far more complicated and better to learn.......it rockzzzz.....tyms it makes us mad toooo..... A.C.Circuits Icon_lol

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@ kevinjo911:

I'm sorry.. I don't really get ur point.. in my post i juz said that derivation in S.chand is better and easier than i cud find on net..! So wat r u saying? its gud or bad.. one more thing i don't say s.chand has simpler explanation for all..!

Subject: Re: A.C.Circuits Tue Mar 09, 2010 4:37 pm

i have been using NOOTAN and S.Chand but i feel S.Chand is better......

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@ kevinjo911:

Then why did u say S. Chand is complicated?

Subject: Re: A.C.Circuits Tue Mar 09, 2010 4:39 pm

complicated in the sense,they have extra stuffs tooooo which are not ter in syllabus......tas why....

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yeah thats right..! But pls be more specific in future while posting..!

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do we have to study Amplifier too..??

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Transitor (common Emitter) amplifier with diagram and input and output signals and characteristics for CE Configuration

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only CE...?? u sure..!

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Yeah confirm..!

http://cisce.org/data/Syllabus%20for%20ISC%202010/Physics.pdf

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Thats greaT...! thanks...!!

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welcome .. A.C.Circuits Icon_exclaim

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Heh WinrRule thnxs for answering Smile

...btw i need the special cases for RC and RL circuits, and is what you posted synonymous to that??....i have notes on phasor diagrams for rl, rc and lcr circuits but could not quite understand the entire meaning of a phasor diagram from what is given in Nootan. So it would be very helpful if you could post something on that too Smile

.....
Thanks once again!! Smile

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Yo Ganu!! Do u have notes on 'Measurement of fringe width using a telescope'??

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Nope br0...! it isnt even in Nootan...im n0t studying it...!

and on the phasor diagrams...its almost like a stuck clock with three hands...! if we pivot the clock on it's GM...and rotate it clockwise... Very Happy

all three hands with respect to each other is at rest...! technically the phase difference is same...! it can be considered as vectors aligned in particular directions and using trig. ratios, the lag/lead is found out...!

that was a nice simile...wasn't it..!! i saw the stuck clock on the wall in my room just now and that was the inspiration.... back to the point...

http://www.animations.physics.unsw.edu.au/jw/AC.html

Subject: Re: A.C.Circuits Tue Mar 09, 2010 9:21 pm

sure i will winRrule....... A.C.Circuits Icon_smile

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In a.c. circuits only these r in syllabus:
R only, C only, L only, LCR series

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ANJANA R U SURE???

I DONT THINK THAT IN AC WE HAVE TO STUDY ONLY THAT MUCH FOR THE NUMERICALS PART...