- #1
issacnewton
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Hello
I have a conceptual question about using Kirchhoff's voltage rule to derive expression of the charge in the RC series circuit when it is being charged by certain EMF. Usually most books start by writing the equation
[tex]\mathscr{E}-iR-\frac{q}{C}=0[/tex]
But when the charging is going on, the current is changing and that means there is non-zero rate of change of magnetic field through the loop which makes the circuit. Kirchhoff's voltage rule is derived from the Faraday's law when the rate of change of magnetic field is zero and so the right hand side of the Kirchhoff's rule is zero. But when we are charging the circuit, right hand side would no longer be zero. So how would we conceive the above equation ? When I was reading online notes of Prof. Walter Lewin of MIT, he said that most of the physics books get these things wrong. Here are the relevant links from his website.
http://ocw.mit.edu/courses/physics/...etism-spring-2002/lecture-notes/lecsup315.pdf
http://ocw.mit.edu/courses/physics/...netism-spring-2002/lecture-notes/lecsup41.pdf
So what do people think here ?
thanks
I have a conceptual question about using Kirchhoff's voltage rule to derive expression of the charge in the RC series circuit when it is being charged by certain EMF. Usually most books start by writing the equation
[tex]\mathscr{E}-iR-\frac{q}{C}=0[/tex]
But when the charging is going on, the current is changing and that means there is non-zero rate of change of magnetic field through the loop which makes the circuit. Kirchhoff's voltage rule is derived from the Faraday's law when the rate of change of magnetic field is zero and so the right hand side of the Kirchhoff's rule is zero. But when we are charging the circuit, right hand side would no longer be zero. So how would we conceive the above equation ? When I was reading online notes of Prof. Walter Lewin of MIT, he said that most of the physics books get these things wrong. Here are the relevant links from his website.
http://ocw.mit.edu/courses/physics/...etism-spring-2002/lecture-notes/lecsup315.pdf
http://ocw.mit.edu/courses/physics/...netism-spring-2002/lecture-notes/lecsup41.pdf
So what do people think here ?
thanks