All Questions
39
questions
21
votes
4
answers
41k
views
Derivation of self-inductance of a long wire
Currently I am stuck, trying to derive the self-inductance of a long wire. According to literature it should be
$$L=\frac{\mu_r\mu_0l}{8\pi}$$
and in literature its derived by looking at the energy ...
- 1,573
4
votes
1
answer
63
views
Why In the following $RL$ circuit, the connection to $b$ must actually be made an instant before the connection to $a$ Is broken? [duplicate]
In Resnick halliday, student 10th edition page - 795. In the topic current decay in RL circuit, the following statement is used, the connection to b must actually be made an instant before the ...
- 43
4
votes
2
answers
2k
views
inductance value of a single turn thin circular coil
the question may seem simple but I haven't found any fitting formula yet. The problem is the following:
consider a single-turn, circular coil made of reasonably thin wire (diameter of the wire much ...
- 506
3
votes
5
answers
19k
views
Transformer: primary side & secondary side current 180 degree out of phase
I am a novice in electrical engineering. I notice that in transformer the secondary side current & current referred to as primary are 180 degree out of phase from each other.
But why it is so, I ...
- 347
3
votes
2
answers
246
views
Using Faraday's law twice
I have trouble understanding Faraday's law when there is an induced current which in turn induces another current in the same circuit. I shall illustrate my confusion with an homework problem and I ...
- 963
2
votes
2
answers
47k
views
Magnetic field at the center and ends of a long solenoid [closed]
A long solenoid has current $I$ flowing through it, also denote $N$ as the turns per unit length. Take its axis to be the $z$-axis, by symmetry the only component of the magnetic field inside is $B_z$....
- 73
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
7k
views
determining Induced emf/current through v x B . l
I am working on a question from my book. I am wondering how they conclude emf is negative in this case. looking at $$ \mathcal{E} = \vec{v} \times \vec{B} \cdot \vec{dl}$$ If there's some implied ...
- 225
2
votes
1
answer
48
views
Find the inductance of the coil by potential difference of the circuit [closed]
A coil is connected in series with a 10.0 k$\Omega$ resistor. An ideal 50.0 V battery is applied across the two devices, and the current reaches a value of 2.00 mA after 5.00 ms. Find the inductance ...
- 23
2
votes
3
answers
1k
views
Maximize Magnetic Self-Inductance Through a Wire
You are given a long length W of copper wire. How would you arrange it to obtain the maximum self-inductance? Why?
I am trying to use the equation
$$L=\mu_o n^2 l A$$
I try to solve it using a ...
- 123
2
votes
0
answers
1k
views
Finding the voltage across an inductor when opening the switch [closed]
Well, I've the following circuit:
In the circuit I want to find the voltage $\text{V}_{\text{Y}_1}\left(t\right)$ as a function of time, after I open the switch (this switch was closed 'forever' ...
- 21
2
votes
0
answers
118
views
Magnetic field due to a double tape line
I have been asked to calculate the inductance of a double tape line :
Now we know that $$ N\phi = LI$$
So let's calculate the magnetic field by assuming an amperian loop like this:
$$\int B.dl = ...
- 361
1
vote
2
answers
3k
views
Magnet falling through a coil that does not form a circuit. Am I wrong or is the mark scheme?
So either this past paper is wrong or my ideas about induction have a problem.
The old exam I am doing asks what happens when you drop a magnet through a coil connected to an Amperemeter, and then ...
- 175
1
vote
2
answers
180
views
Electromagnetic induction at the centre of a cylinder with rotating current [closed]
A long circular tube of length 10 m and radius 0.3 m carries a current I along its curved surface as shown. A wire-loop of resistance 0.005 ohm and of radius 0.1 m is placed inside the tube with its ...
- 452
1
vote
1
answer
68
views
Loop law and charge redistribution [closed]
Addendum:
I have just read Strict(er) adherence to homework guidelines? and think that this is the reason why there have been three votes to close this topic. Notice, though, that I am not asking for ...
- 558