Doubt:

Question

Doubt:

aravindg · Answer

I understand that average electric energy density

$$U=\dfrac{1}{2} \in_0 E^2=\dfrac{1}{4} \in_0 E_0^2$$

But what is the normal E? I know that E_0 is the maximum value of E. Also why is E=E0/root (2)?

aravindg · Answer

@Vincent-Lyon.Fr

aravindg · Answer

By  normal E  I meant the E without any subscript.

aravindg · Answer

Another doubt: http://screencast.com/t/NfA4N7qD4wEm Why is the torque due to gravity mg/2? Or a better question will be about which point are both these torques evaluated? A diagram would be great!

sidsiddhartha · Answer

it'nt it the RMS value?

aravindg · Answer

Even I was thinking like that. But isnt rms value associated with voltages and currents? How does it come into picture when we have an electric field?

miracrown · Answer

remember torque is equal to the force times distance

miracrown · Answer

|dw:1399971142034:dw|

and as you want one end lift we get half of the total weight the mass of the wire is m
so we use mg/2