All Questions
20
questions
58
votes
7
answers
21k
views
Cyclist's electrical tingling under power lines
It's been happening to me for years. I finally decided to ask users who are better with "practical physics" when I was told that my experience – that I am going to describe momentarily – prove that I ...
- 180k
10
votes
4
answers
4k
views
Where does the extra energy come from in an LC circuit?
In an LC circuit, or an LC tank, the capacitor discharges in one direction
through an inductor and then the inductor seems to carry energy in the form of a magnetic field , to charge the capacitor ...
- 607
3
votes
1
answer
3k
views
Magnetic Flux conservation
My teacher said that after switch is shifted (after very long time), $\phi_i = \phi_f$ $\implies i_oL = i3L \implies i = \dfrac{i_o}{3} $ where $i_o$ is $\dfrac{\varepsilon}{R}$
So the initial ...
- 375
1
vote
3
answers
319
views
Significance of sliding switch in a LR circuit
The following image and statement are from my textbook Concepts of Physics on the chapter "Electromagnetic Induction", topic 38.6 "Growth and decay of current in an LR circuit", ...
- 5,306
1
vote
1
answer
823
views
Differential equation in RL-circuit
I am self-studying electromagnetism right now (by reading University Physics 13th edition) and for some reason I always want to understand things in a crystalclear way and in depth. Now look at this ...
1
vote
2
answers
144
views
Inductor with ac supply
When an ac source is connected with an inductor we have a continuous change in voltage and current across the inductor.
According to farady and lenz law we will get an equal and opposite voltage ...
- 1,441
0
votes
0
answers
111
views
How to find the canonical equations of the RLC circuit
First, I consider the LC circuit with an ion in the capacitor, which is like this:
The current $I$ can be derived easily by using Shockly-Ramo theorem
\begin{equation}
I = -\frac{qp}{dM} + C\dot{U} \...
- 68
6
votes
2
answers
1k
views
Why is all of the energy from a battery stored on an inductor but only 50% on a capacitor?
I am learning about inductors and capacitors and we derived the energy stored on a capacitor to be 50% of that delivered by the battery. We did this considering a circuit of a capacitor connected to a ...
- 3,997
4
votes
5
answers
2k
views
Isn't the inductor equation negative?
The inductor "resists" change in current. So say you measure the voltage across the inductor from point A to point B - the current is flowing in from A towards B. Now say the current is increasing. ...
- 2,009
3
votes
3
answers
1k
views
Kirchhoff law and Inductors
I am struggling with using Kirchhoff's rule in circuits with Inductors. Looks like if you have an inductor, we have Electric field (E) that is created using a time varying magnetic field and that E is ...
- 1,481
2
votes
3
answers
535
views
Why can't the current in a solenoid be changed rapidly?
Why can't the current in a solenoid be changed instananeously? My reasoning is since the current in a solenoid is given by a integral:
$$I(t) = \frac{1}{L} \int_{t_0} ^{t_f} V_Ldt$$
then if $t_f = t_i ...
- 548
2
votes
3
answers
644
views
How is EMF still induced in an incomplete/open circuit?
I understand that current can't flow through a coil if it is not complete, but surely this means that if a magnet is dropped through the coil, no EMF would be induced either, since work is done when a ...
- 31
2
votes
1
answer
153
views
Quantization of a waveguide: he only has one of the two E.O.M in his Lagrangian. How can the quantization be correct?
I am following this reference, appendinx C and D, around page 61
The goal is to quantize electric of current of propagating wave in a waveguide.
Classical E.O.M:
We model a waveguide by a ...
- 1,450
2
votes
1
answer
1k
views
How do I show for an ideal transformer $M^2=L_1L_2$?
I've been stuck on this problem for about an hour.
In an ideal transformer, the same flux passes through all turns of the primary and of the secondary . Show that in this case $M^2=L_1L_2$, where $...
- 5,371
2
votes
1
answer
290
views
Mutual inductance - induced magnetic flux in the primary
Let there be two coils, L1 (with self inductance L1), and L2, with self inductance L2.
The first coil is connected to a sinusoidal supply, and the second one is connected to a resistor load, as shown ...
- 21