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Energy stored in an inductor 
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#1
Nov509, 07:38 AM

P: 10

so the amount of work done to drive the current through the inductor is given by
dw=Eidt where E is the emf of the variable voltage source.We put E=+L (di/dt). can you please tell me why we put that value?? (i know the induced e.m.f on the inductor is  L (di/dt) thanks 


#2
Nov509, 09:32 AM

HW Helper
P: 4,435

while calculating the amount of work done we have to take the integration. For that we have to reduce the expression of dw in single variable
So dw = Eidt = L*i*di/dt*dt = L*i*di. Now take integrations to get the energy stored in the inductor. 


#3
Nov609, 05:23 AM

P: 10




#4
Nov609, 08:19 PM

P: 540

Energy stored in an inductor
The reason why it's positive for your given equation, is because positive work must be done to induce the current. We need only the magnitude of E then. 


#5
Nov809, 04:24 AM

P: 10

thanks again. 


#6
Nov809, 04:38 AM

HW Helper
P: 2,323

The induced emf is Ldi/dt; the negative sign just indicates it opposes the battery's emf. The electrons pushed through the inductor must overcome a voltage of Ldi/dt (that is, they must overcome an increase in potential of magnitude Ldi/dt), so they gain Lidi/dt of potential energy per unit time. This gain in potential is what the energy stored in the inductor really is.



#7
Nov809, 08:29 AM

P: 540

Consider a circuit with an applied emf, resistor, and inductor, where the current varies with time. If the current is increasing (di/dt > 0 ), then the selfinduced emf opposes the direction of the applied emf. If the current is decreasing (di/dt < 0), the selfinduced emf is actually oriented in the same direction as the applied emf. In both cases, the selfinduced emf has orientation that always opposes the "change in current", not the "applied emf." 


#8
Nov1309, 08:27 AM

P: 10

thanks :)



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