All Questions
Tagged with electromagnetic-induction electrical-resistance
41
questions
2
votes
2
answers
117
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Confusion related to emf in a loop
To calculate the current in a closed loop of resistance R subject to a changing magnetic field which generates an emf $ \epsilon= - \frac {d(\phi)} {dt} $, we use the relation ohm's law in the form.
$\...
- 292
0
votes
2
answers
119
views
Why current does not instantly reach maximum value in an $LR$ circuit?
In an $LR$ circuit, I read that when an resistor $R$ and an Inductor $L$ are connected to an emf $E$ source in series, and the switch is switched on, the current flowing in the circuit does not ...
0
votes
1
answer
81
views
How do non-ideal inductors behave in a circuit?
I cannot comprehend how
can we break a seemingly non-ideal choke coil into just a pure resistor and inductor in series according to the following solution of a question.
Considering the data in the ...
- 5
0
votes
2
answers
49
views
$I²R$ loss in case of transformer
Suppose we have a 100 V A.C. supply, and we connect a 1 ohm resistor with it. Now the current through the resistor will be 100 A. Now we connect a 1:2 step up transformer with the A.C supply, and then ...
- 11
1
vote
0
answers
42
views
Is my reasoning about $ε = iR$ correct, where $ε$ denotes induced emf, $i$ denotes induced current, and $R$ is resistance of loop [closed]
I came up with the formula, $ε = iR$, where $ε$, $i$ and $R$ denotes induced emf, induced current and resistance of loop respectively. I did the following reasoning to prove this formula, am i right?
- 19
1
vote
1
answer
90
views
Validity of Ohm's Law due to Induced Electric
If we have a conducting loop of resistance R in a region of varying external magnetic field, how can we determine the current through the loop?
First, if we consider Ohm's Law, then we get that
$$\...
- 301
1
vote
3
answers
128
views
$RL$ Circuit Initial Condition - Why is $I$ continuous?
In a simple $RL$ circuit with a switch, the switch is closed at $t = 0$. Then the differential equation we are solving is $V_0 -L \frac{dI}{dt} = IR_0$, and the solution is $I(t)=\frac{V_0}{R_0}+ke^{-\...
- 171
1
vote
3
answers
97
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Understanding voltage in AC
With DC, for example, a battery, it's easy to understand that one terminal is more negatively charged then the other, so that there is a potential difference between the terminals, which creates a ...
- 282
1
vote
1
answer
254
views
Does the electric field ($E$ caused by induction) of a moving conductor in a magnetic field drop when connected to a curcuit?
We know that when a conductor moves in a homogenous magnetic field that is perpendicular to itself due to the amount of electric charge gathered on one end of the conductor( as a result of the lorentz ...
1
vote
1
answer
228
views
Current when inductors charging in parallel are discharged in series
We started discussing DC RL-circuits in class and were analyzing the following circuit
The scenario is the switch has been closed for a long time so the current through both 2-ohm resistors is the ...
- 11
0
votes
1
answer
99
views
In a LR circuit, Why do the current rate of increase decreases with time? [closed]
In a LR circuit, the current rate of increase decreases with time until it reaches zero eventually and that is when the current become steady. My question is why the current rate of increase decreases ...
- 959
1
vote
2
answers
308
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Regarding Lenz's Law presented in hyperphycsics
The following diagram is presented in hyperphysics as an introduction of Faraday's Law and Lenz's Law.
If the red arrows represent the direction of current, then what do the positive and negative ...
0
votes
1
answer
148
views
What effects do inductors have on circuits?
The above diagram is a simple circuit containing an inductor.
According to the right hand grip rule, it can be deduced that the magnetic field is to the right. But the magnetic field produced by the ...
- 605
1
vote
1
answer
131
views
Emf induced by a solenoid
Could someone please clear my confusion regarding this concept and point out what is wrong with my argument:
Say we have a simple circuit as shown in the image:
Why is the potential difference ...
user343558
1
vote
0
answers
98
views
Square coil circuit and variable magnetic field problem
I am attempting to solve the following problem.
A square coil of side $l = 40.6 \ cm$ and resistor $R = 95.5 \ \Omega$ is contained within the $xy$ plane. Within the same region a magnetic field, ...
- 115
0
votes
1
answer
100
views
Overwhelming confusion regarding electromagnetic induction in Step Up Transformers
Suppose I've two step up transformers $A$ and $B$, each with same number of coils and same length of wire and same material of input wire. But $A$ has an output wire of higher resistance than $B$.
...
- 1,168
0
votes
4
answers
543
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What is Ohm's law for induced current?
In this book it is written on pg $313$ in the last paragraph that Ohms law i.e. $R (constant)=\frac{\epsilon_{ind}}{I}$ is valid for induced current in a circuit. They define $R$ to be the sum of the ...
- 480
0
votes
1
answer
52
views
Why does the same amount of current flow through both resistors after opening the switch S? [closed]
Why does the same amount of current flow through both resistors after opening the switch S?
- 33
-3
votes
2
answers
122
views
Many things that plug into the wall for power, use a transformer inside, so are not physically connected to the mains, do they consume mains energy?
Question
Many things( hairdryers etc etc ) that plug into the wall / mains for power, use a transformer inside, so are not physically connected to the mains, do they consume mains energy ?
I assume ...
- 105
2
votes
2
answers
2k
views
Current decay in RL circuit
I guess this has been asked before many a times. But I searched for it and couldn't find the question. Any kind of qualitative answer will be really helpful.
When a magnetically charged inductor is ...
- 23
1
vote
3
answers
834
views
Does load on electromagnet affect its current?
If we make an electromagnet by winding 3000 turns on 5-inch-long cast iron bar, and provide $12 \;\text{V}$ and $2 \;\text{A}$ of current, it will produce the magnetic field with certain magnitude.
...
- 129
1
vote
0
answers
47
views
Incongruent expressions for $E$- and $B$-fields based on approach
I am having two issues with Maxwell's equations in the following problem:
A thin conducting disc has radius a thickness b and electrical
resistivity ρ. It is placed in a uniform time-dependent ...
- 535
0
votes
1
answer
72
views
How does current/component voltage phase difference calculated in pure circuits remain the same for mixed circuits?
In class, we derived the phase difference values between the component voltage and the circuit current for pure inductive and capacitive circuits. Later, while doing LR, RC, and LC circuits, we used ...
- 256
1
vote
1
answer
127
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How can a coil self-induce voltage at $t=0$?
Assume you have a resistor and an inductance in series. When a DC supply is connected at t=0, the coil is inducing an opposing voltage, which is the same as the DC supply's voltage. The current ...
- 11
1
vote
3
answers
596
views
Intuition in an LR circuit -- Why does rate of increase in current decreases with time?
Consider the below LR circuit.
The current law for the circuit is:
$$i=\frac VR(1-e^{- \frac {Rt}L})$$
And Voltage across inductor is:
$$L\frac {di}{dt}=V(e^{-\frac {Rt}{L}})$$
This means that the ...
- 1,568
0
votes
2
answers
92
views
Nature of the current produced by a magnetic field?
Consider a loop made off with a conducting material with resistance $R$. This loop is in a uniform magnetic field. Then, thanks to Faraday's law, we know that a current will be induced in the loop. My ...
- 183
0
votes
2
answers
448
views
Inductors in an AC circuit
I have read that inductors oppose change in current flowing in the ac circuit. For example, when current starts increasing it induces an emf in the opposite direction to oppose the current from ...
- 163
1
vote
1
answer
73
views
Confusion regarding inductor connected to an AC source
Suppose I connect an inductor to an ac source. Now a time varying current is produced and this causes change in magnetic flux linked with inductor coils and hence an induced is generated. But why ...
- 163
0
votes
1
answer
779
views
What is $v(t)$ in a sliding conducting rail in a magnetic field?
This is problem 7.7c from David J. Griffiths - Introduction to Electrodynamics.
A metal bar of mass $m$ slides frictionlessly on two parallel conducting
rails a distance $l$ apart. A resistor $R$ ...
- 3
3
votes
2
answers
232
views
Now what will happen in this circuit?
Consider a circuit as shown in this figure below-
Assuming switch S1 is closed such that current flows in loop ABCDE for a long time and steady state is reached.
Now, my question is simple, suppose (...
- 676
0
votes
1
answer
157
views
Inductors problem
In figure, the switch is in the position 1 for a long time. Then the switch is shifted to position 2 at $t=0$. At this instant, the value of $i_1$ and $i_2$ is
Well I'm confused over what will happen ...
- 253
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
1
answer
1k
views
Do transformer follow Ohm's Law?
We khow that due to Ohm's Law,
$I$ is proportional to $V$
So if $V$ rises, $I$ should rise too. But in a transformer when $V$ rises, $I$ lessens. Why does this happen? It seems like transformers ...
- 1,400
0
votes
2
answers
664
views
LR circuit with DC voltage
In a LR circuit connected with battery what happens if $R=0$ assuming the switch is closed at $t=0$? Will emf be induced in the inductor? I am confused so please help me.
0
votes
2
answers
257
views
In a circuit consisting of and inductor and an alternating current source shouldn't the current at $t=0$ be zero, assuming $E=E'\sin(\omega t)$?
Why is emf across inductor infinity at t=0?
Please excuse my poor handwriting.
- 23
0
votes
1
answer
1k
views
What is 'arcing' at switch contacts in LR circuits when current changes instantaneously?
I am studying from Neil Storey's Electronics book and I can't understand the following paragraph:
"We know that the current stabilises at a value of V/R. If the switch is now opened, this would ...
3
votes
3
answers
9k
views
At $t=0$ the voltage across the Inductor will immediately jump to battery voltage. Why?
While reading transients i come to read......
"the voltage across the inductor will immediately jump to battery voltage (acting as though it were an open-circuit) and decay down to zero over time (...
- 1,441
1
vote
0
answers
362
views
Induced current by changing magnetic field and resistance
Let's say we have a wire loop with resistance $R$ in a changing magnetic field. The changing field will induce an electric field and hence an emf $\mathcal{E}$ around the loop. The induced E-field is ...
- 263
3
votes
2
answers
1k
views
Inductors in parallel. Link between inductance and current in a D.C. circuit
A problem from the FIITJEE review package:
Or, paraphrased:
When two inductors in parallel connected to a battery with some internal resistance, what is the current through each of the inductors ...
- 272
0
votes
1
answer
778
views
Behavior of coil and resistance in DC circuit [closed]
I have a simple circuit of a coil parallel to a resistance and then in series with another resistance. I wanted to understand the behavior of this circuit so I ran a simulation, and what I noticed is ...
- 125