All Questions
39
questions
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31
views
Current sensitivity in transformer scheme with SQUID
I've tried to determine the maximum current sensitivity in this transformer scheme but I'm not sure if my solution is valid. I need to find the relation between the current in the input transformer ...
0
votes
1
answer
35
views
What does "90 degrees ahead of phase" mean in inductance problems?
I've been working on this homework problem and I have determined that the induced EMF on the right coil is sin(x-90). However, I do not understand what "ahead of phase means." When I graph ...
- 101
1
vote
0
answers
131
views
Coilgun projectile force calculation
Please excuse me if I am completely wrong because I am a 9th grader but I hopefully am able to explain briefly about my problem. I was trying to create a function to calculate the Force of an iron ...
- 11
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
0
votes
1
answer
194
views
Self-inductance of a finite solenoid
Where did the $l$ in the denominator come from? I am talking about the $l$ in muNI/2l[...]?
I can't match LHS and RHS.
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
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
1
vote
1
answer
47
views
Induced current in a rotating coil? [closed]
I'm a little bit confused with this problem: Find the induced current in a rotating coil with resistance R and inductance L. What I tried is this (assuming N=1):
$$\epsilon =-\frac{\text{d}\phi}{\text{...
- 27
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
0
votes
1
answer
201
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The self inductance of the motor of an electric fan is 10 H. In order to impart maximum powr of 50 Hz, it should be connected to a capacitance of [closed]
how can i solve this
(*)The self inductance of the motor of an electric fan is 10 H. In order to impart maximum powr of 50 Hz, it should be connected to a capacitance of
what is the concept behind ...
- 15
0
votes
1
answer
1k
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Would the following 2 solenoids repel or attract each other? [closed]
Question:
Describe what will happen to two solenoids that are arranged next to each other as shown. The solenoids are the same length, and have the same number of turns and current flowing through ...
0
votes
2
answers
802
views
Solenoid Length In Inductance Formula
For a long solenoid, when the formula describes solenoid length, is it referring to the length of the wire wrapped around the magnetic core or the length of the core?
- 51
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
0
votes
1
answer
1k
views
Motion of a magnet inside a solenoid
I have a homework problem where a bar magnet is placed halfway inside a horizontal solenoid. A cut away shows that the magnet's north pole points to the left of the page and the south pole is outside ...
-1
votes
1
answer
195
views
Square loop moving into an homogenous magnetic field. How do i define the area as a function of time? [closed]
Looking through some old exams i found this problem where im supposed to derive an expression for the induced emf, ${\mathcal {E}}$(t), of a square loop moving into an homogenous magnetic field and ...
- 33
0
votes
2
answers
146
views
Conducting loops attracting each other
The problem is the following
Two identical, perfectly conducting loops are far apart and share the same axis. Each has self-inductance $L$ and a current $I$ flowing in the same direction, so the ...
- 1,161
2
votes
0
answers
1k
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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
1
vote
2
answers
137
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Current in the inductor at $t=0$
$L_1 = 5H, L_2=0.2H, M=0.5H, R_0=10 Ω$, and $i_g=e^{-10t}-10 A$. I need to find $i_2$.
I've started with DE
$$i_2R_0+L_2(di_2/dt)+M(di_g/dt)=0$$
and solved it for $i_2$, so $$i_2=0.625e^{-10t}+Ce^{-...
- 111
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
808
views
Is induced EMF proportional to the square of the number of turns of a solenoid?
In order for this question to be clear I must first give some context:
Consider a 10cm long solenoid (solenoid A) of radius approximately 1cm with 400 turns.
Let the current in $A$, $I_A$, change ...
- 2,470
1
vote
1
answer
357
views
Potential difference across the strips of an inductor [closed]
The voltage across the ends of an inductor is $L (di/dt)$. Applying the loop law $V = L(di/dt)$, so the voltage across the strips at a distance x measured from the "LEFT END" should be $V \frac xl$ ...
- 361
0
votes
2
answers
23
views
Magnetic energy in coil at time $t$ after circuit being hooked up
"A coil with inductance L = 50 mH and R = 600 ohm is coupled in series with a resistance R = 200 ohm to a battery with the voltage 12 V. How great is the magnetic energy in the coil at the time t = ...
user180617
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
0
votes
1
answer
1k
views
Induced voltage of a coil inside a coil
I have the length of the first coil, the number of turns in both, the current through the first coil and the cross-sectional area of the coil inside. I want to find the induced voltage. I know I ...
- 173
1
vote
4
answers
408
views
Electric Field in an Infinite Alternating Current Solenoid
Reading Wangsness's Magnetic Fields book I stumbled upon an explanation I can't understand. It goes like this: There's an alternating current solenoid with radius $a$. We know the magnetic induction ...
0
votes
1
answer
107
views
Will there be any current induced in a purely capacitive circuit?
Will current be induced in a purely capacitive circuit if a magnetic field B is present perpendicular to it and a movable conducting wire completing the circuit is moving with a velocity v.
Just want ...
1
vote
1
answer
132
views
How to simplify the maths to determine the mutual inductance between two multi-layer rectangular coils of arbitrary dimensions?
I am experimenting with wireless power transfer. The maths to directly determine mutual inductance between two multi-layer rectangular coils of arbitrary area, separated by an arbitrary distance, ...
- 11
2
votes
1
answer
1k
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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
2
answers
47k
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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
1
vote
1
answer
1k
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Is Magnetic field inside solenoid dependant on volume of its shape?
There are two types of solenoids: one cylindrical, one spherical. Let's assume the dimensions of the cylindrical solenoid are set such that its base radius is that of spherical solenoid $a$, and the ...
- 265