An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In a electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons.The SI unit of electric current is the ampere, or amp, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit Electric current is measured using a device called an ammeter.Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.
Where can I get actual demonstration that a 1/60 sec current can move the magnet. That is. You just apply 1/60 sec current without other power in the middle of it, will the magnet move that fast in 1/60 sec? Or does motor runs because of inertia of the previous rotation?
$$B = \frac {\mu_0 I}{2 \pi r} $$
By Right-hand Grip Rule, the direction of the magnetic field by wire in y-axis is into the paper (z)
while the direction of the magnetic field by wire in X-axis is upwards (+i)
The answer state the Magnetic field is in the (i - y) direction though.
Next...
All the equations I have seen have a component that is unknown. Also, if possible do let me know if there is a software I can use to model or analyze data related to eddy currents
My reasoning is as follows: with the short circuit present, a 0 resistance can be considered between the terminals. Then, since the only objective of the short circuit current ##I_{SC}## is to give information about the Thevenin equivalent resistance and the open circuit voltage (the existence...
Hello there, I've worked through this problem and I would just like to check whether I've understood it correctly. I found ##\vec H##, ##\vec B## and ##\vec M## using Ampere's Law and the above relations as I would for any thin current carrying wire and these were my answers:
$$\vec H = \frac I...
hi guys
i have an assigment of deriving the current between the plates of a vacuum tube as a function of the potential bias applied on the upper plate
from what i had found this relation is called Child-Langmuir law and states that :
$$I = K V_{d}^{3/2}$$
from what i find online i can derive it...
The source of the 0.824×10-4 value is
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/denpar.html .
I also looked at the Planck 2018, paper I but could not find a value for Ωr. I searched the internet with:
radiation density cosmology friedmann omega
but I had no success. I also looked at...
I have nearly finished my homework, but am blocking at one of the simplest questions...
I'm going to let ##\rho=0.094\,\Omega/m##
Since the magnetic flux is increasing, then, by Lenz's law, the current in both loops is counter-clockwise.
If we only look at the left loop, then...
I have defined 5 currents but I can't seem to solve it.
I1+1=I2 (left)
I5+1=I4 (right)
I2+I4=I3 upper node
By KVL I have determined that I2 and I4 are equal, but I cannot determine the specific current across each resistor. Thank you for your valuable help.
First and foremost, I've studied voltmeters and ammeters on my own, and online there aren't many resources to do so... forgive me in advance for eventual silly questions/doubts :)
I managed to calculate(intuitively) a tension of ##30.0V## per resistor, with basic procedures.
However, I'm...
I'm having a few troubles understanding a few things about this circuit...
Firstly, what does "In light of this, the potential between the resistors is ##16V##" exactly mean? If current isn't flowing, how could there be a potential between resistors?
Secondly, how does current flow with the...
Hi there, I've worked through most of this question but I'm stuck on the final part, showing that total bulk current ##I_B## is equal and opposite to total surface current ##I_S##. I calculated ##\vec H## the normal way I would if I was looking for ##\vec B## in an infinitely long cylindrical...
So, I started by writing down conditions imposed by Kirchhoff's laws, coming up with a system of 3 equations with the 3 unknown currents:
$$
\left\{\begin{matrix}
9V-8\Omega I_{8}+6V-4\Omega I_{4}=0 \\
6V-4\Omega I_{4}+3V-2\Omega I_{2}=0\\
I_{2}+I_{8}=I_{4}
\end{matrix}\right.$$
But...
so far on this question i have calculated the phase voltage as 415 Volts using by multiplying the line voltage by root 3. i know how to calculate (d) but am struggling with finding the equations to satisfy
I integrated the second equation given in the form (integral)di= 1/L * (integral) V *dt and I got an answer of 3.52 for the current at 0.4 seconds, anyone can let me know if this is correct?
Hello there,
I've been working through a task (that doesn't have an answer sheet or explanation) in which we plot I against V for three different diodes. Each has a different threshold voltage and displays the usual charcteristic curve. The final question is this:
"It is suggested that the...
This is supposed to be very basic, where the loop is held there is a declining magnetic field in direction (-z), therefore the current is supposed to be clockwise. However in the answers it is said the the current is anti clockwise. That doesn't make sense to me.
Is there a mistake in the answers?
If i was conducting an experiment where i wanted to determine the ion selectivity of an ion channel that has a similar structure to voltage gated Na channel but is different in ion selectivity, would i use a voltage clamp or current clamp to figure this out. Also would i use a cell line or an...
1)$$\frac{Q}{\Delta V}=\frac{\kappa\epsilon_0A}{\ell}\Leftrightarrow\Delta V=\frac{Q\ell}{\kappa\epsilon_0A}$$$$I=\frac{A\Delta V}{\ell\rho}=\frac{Q}{\kappa\epsilon_0\rho}$$
2) The charge is decreasing by ##\Delta Q##, so ##Q(t)=Q-\Delta Q##.$$I=\frac{\Delta Q}{\Delta t}\Leftrightarrow\Delta...
Hi,
I'm aware it is an odd question. Consider a ##k##-terminal electrical device as black-box.
We know from KLC and KLV that just ##k-1## currents and ##k-1## voltages are actually independent (descriptive currents and voltages).
Furthermore we generally expect there exist ##k-1## relations...
The main problem is the verse of the 2 currents ## i1 ## and ## i2 ## . I think they both go clockwise, so in the node A we should have ##i1+i2=20A##. Now let's apply the second law (going clockwise). So ##ΔV1-R1*i3 - R2*i4 + ΔV2=0##, where ##i3## and ##i4## are the currents which pass through...
Actually, is not a doubt as a question, in which there is wrong or right. I just want to update myself with respect to the current physicists opinion about the Copenhagen interpretation of Bohr and Heisenberg. Summarizing, there is a consensus among the majority? In another words, there is still...
Neglecting the air resistance, is it more difficult for a biker with a proper gearing in his bike, to increase his speed by 5 kph if his current speed is 20 kph rather then if his speed is 10 kph?
It seems that the answer is yes according to the energy formula but I've asked several bikers and...
In a certain anisotropic conductive material, the relationship between the current density ##\vec j## and
the electric field ##\vec E## is given by: ##\vec j = \sigma_0\vec E + \sigma_1\vec n(\vec n\cdot\vec E)## where ##\vec n## is a constant unit vector.
i) Calculate the angle between the...
Could someone please help.
i need to connect a 12vdc motor which can draw 16 amps
to a switch that has an led on it. the led is rated at 3v 20mA.
The power supply i am using is rated to put out 12vdc at 30A
I thought of the possibility of adding a resistor to the positive pole of the led.
In...
Consider a circuit with a witch, capacitor and an AC voltage source.
The sinusoidal AC voltage source is depicted in the following graph:
We know that, ##Q = CV##
##\frac{dQ}{dt} = C \frac{dV}{dt}##
##i = C\frac{dV}{dt} \tag{1}##
So from the graph, the voltage increases rapidly around ## t =...
I am struggling with the angles. Since the conducting wire is moving down for it to be stand still, the force should be opposing it, hence the current should be from Right to Left.
I am confident of the Force direction and its value is if ## I ## is the current
##F = ILB (N)## since L and B...
https://www.physicsforums.com/attachments/267955 I think i should apply kirchkoff rules so I can find i1,i2,i3 R1,R' but I don't have enough information and I don't know how to have those informations .What is your ideas?
Hi all,
Managed to get an answer out, but unfortunately, it doesn't correspond with the answer given ( –3.09 A)
Would appreciate if one could check out what I did wrongly here:
## V_{1}=2\times 5=10V ##
At node 2:
## \dfrac{V_{1}-V_{2}}{2}=12+\dfrac{V_{2}}{1}+\dfrac{V_{2}-V_{3}}{2}##
We can...
Disclaimer: The solution to this question has already been posted by my instructor. I made this post to understand why my solution is wrong or if the instructor is wrong, since their explanation does not make sense to me.
My reasoning:
Using the fact that the magnetic torque on a...
The problem seems to be easy but i don't get the correct answer.
a. The current in the field coils. The net resistance of Rf = 106 and Rr = 5.9 is
## Reff = \frac {(106 * 5.9)} {(106.9 + 5.9)} = 5.54 ##
## \frac { 120 - E} {5.9} = 4.82 => E = 91.562 ##
## If = \frac { 120 - 91.562} {106} =...
##\vec \tau = \vec \mu \times \vec B -eq1##
## F = I \vec l \times \vec B -eq2 ##
The forces i have indicated
The magnetic moment is coming out of the page.
I am only attempting only the part (a) as of now
a. The force calculations are
F1 = 1.4*0.22*1.5 = 0.462 +X direction
F2 = 1.4*0.22*1.5...
I am studying the theory of force on a current carrying conductor in a uniform magnetic field, the Force is ## F=ILB##. I am slightly confused here let us say the conductor is placed in the uniform magnetic field ##B##, then if the current is passing through the conductor then that current would...
Good afternoon guys,
I was making some researches about building my own EV and its' specifications but I have a few no direct answered questions and some of them I humbly ask the help for you guys, based on the configuration example below.
Considering that I hypothetically have an electric DC...
My teacher proved it like this
I= ##\frac {E}{R+r}##
Where R is external resistance
And r is internal resistance
E is emf of the cell,
Now we can write it like this
I= ##\frac {E}{(√R-√r)²+2√R√r}##
if R=r then the denominator value will be minimum but i am unable to understand that why this is...
Suppose you have a non-uniformly doped piece of semiconductor (without an applied bias) such that the acceptor dopant concentration Na(x) decreases from left to right (as x increases). In this case, the equilibrium hole distribution p(x) will not be uniform since then there would be a net drift...
The magnetic energy of a current carrying spring, with ##N## turns, length ##x## and cross sectional area ##A##, is $$E_m = \frac{\mu_0 N^2 I^2 A}{2x}$$The (negated) spatial derivative of this yields a quantity with dimensions of force,$$F = - \frac{dE_m}{dx} = \frac{\mu_0 N^2 I^2 A}{2x^2}$$How...
Okay, so according to the transformer equation, VpIp = VsIs
In this question, I know I have to calculate Ip.
I think given, Vp = 9V, Vs = 120 V
Now I don't know what to use in the value of Is.
Please help!
The answer is 2.32 A.
So the magnetic field induced at the center of a current-carrying loop is given by:
B = μ0 i /2r
where r is the radius of the loop
In the case of a semi-circular loop, this becomes
B = μ0 i /4r
In the question, i = 2A, r1 = 1m and r2 = 2m
So, field induced at the center of first semicircular...
I've been researching dielectric breakdown for a while and came across this interesting experiment:
https://tore.tuhh.de/bitstream/11420/1160/1/Size_dependence_of_the_dielectric_breakdown_strength_from_nano_to_millimeter_scale_TUB_Doc_version.pdf
0.3mm of BaTiO3 was placed between two...
Yup, it's mutated to be more contagious and has a higher viral load in patients, but does NOT change the severity of symptoms. It is a mutation that was noted back in Feb., 2020 of the original version from China, it has spread worldwide.
52 page research article in Cell ...
I am new to this forum, and this is my first post. Please bear with me if my query has any inaccuracies.
In the attached figure, a coil is wrapped around the central arm of a flat H-shaped thin metallic plate (such as iron). DC current flows through the coil and magnetizes the arm. At the...