Electric current Definition and 172 Threads

How does the current is reduced by the resistance. How is the rate of charge flow decrease in the whole circuit if the variable resistor is placed in the middle of the circuit?

what is electric current...a scaler or vector?? ...well I personally believe that it is somewhere in between the two extremes (what is not 0,need not be an 1 either :oldbiggrin: ) ...particularly because of the strange similarity we see in vector addition and phasor addition)...some people...

Homework Statement (sorry for possible notation errors, that might arise during the translation) Why an electric current passing through a closed loop, can be defined only in stationary conditions? Homework Equations The Attempt at a Solution I think that the reason is that, if the...

How is the potential difference done? How do they make electrons move? Do they use electrical field using positive (to atract them) or negative charges (to repel them)? Do they use variables magnetic fields?

Hello everyone, I have a problem which is a conceptual misunderstanding concerning electric current. I understand that different charges attract and like charges repell, I want to know what really happens inside the wire so a lamp lights immediately when we press on the light button. an...

I'm confused that what is the main difference between the magnetic field produced by electric current and the magnetic field produced by a real bar magnet? As per my knowledge the magnetic field of Current does not have any poles. Then how a solenoid and a bar magnet's magnetic field be similar...

Hello again :) I've got a serious problem. Generally I know why current flows (free electrons and voltage). But some days ago I was considering about regular battery and electrical circut. Free electrons in wire flow along circut, ok, that's fine and understandable. But how does battery...

Homework Statement A circuit is constructed with five resistors and one real battery as shown above right. We model. The real battery as an ideal emf V = 12 V in series with an internal resistance r as shown above left. The values for the resistors are: R1 = R3 = 57 Ω, R4 = R5 = 75 Ω and R2 =...

Hi, so i want to ask what's the function of the split between the commutator? my guess is to temporarily separate the opposite electrons flow between the coil and external circuit after the half cycle? so that's why the current is reversed? please i really need someone to explain how the...

Wave propagation speed or velocity of propagation (VoP) of a transmission medium is ratio at which the wavefront of the signal passes through the medium to the speed of light in vacuum. For example, copper has a wave propagation speed ~0.951. What is a wave propagation speed through a living...

How is the current that pushes electricity through the space between the two plates of the capacitor called?

Homework Statement ##i=20\sin(377t)## is the current function. in the time interval 0-1/120 sec what is the charge that passed Homework Equations $$q=\int_0^t i dt$$ The Attempt at a Solution $$q=\int_0^{1/120} 20\sin(377t) dt=\frac{20}{377}\int_0^{3.14} \sin x dx$$ $$q=-\frac{20}{377}\cos...

Homework Statement calculate the electric current in the 20 ohm resistor The Attempt at a Solution I have no idea where to start, but i thought maybe you should calculate the voltage first and then the voltage over the 20 ohm resistor.

Homework Statement Two 16 Ohm resistors connected in parallel are then connected in series to a 10 Ohm resistor. The entire setup is connected to a 9 V battery. What is the current through the 10 Ohm resistor? Homework Equations V=IR I1+I2=It 1/Rt= 1/R1 + 1/R2 The Attempt at a Solution So I...

Hello! Supposed I had 2 identical copper wires, I'll call them A and B. I insulate wire A with whatever the standard wire insulation is, and leave wire B alone (uninsulated). I'll now send an identical signal (same voltage and power) through each wire. Will the current be identical at the...

I read in class 10. I am having problem understanding magnetic fields, magnetic flux,magnetic flux density,magnetic field strength,magnetic permeability and strength of magnetic field produced due to a straight and closed loop current carrying conductor at a certain point at a certain distance...

Could you advise me, which type of device could be purchased in general electronic stores (or at least in specialized ones) and which are capable to modify electric current in wide spectrum? Desirable in small power range. Such as to set a pulse width, harmonic, frequency, pulse duration, power...

The photon is the force carrier of the electromagnetic force, I'm not talking about photonics but hasn't the effect of every electric current dc or ac ever been due to photons acting only? In theory couldn't we have an electron-less current due to only photons but still with the same effects?

Homework Statement In other words, I have an equation: ##\nabla \times \vec B =\mu _0 \vec j##, where ##\vec j = (f(x,y),g(x,y),0)##. I need to find ##\vec B##.Homework Equations The Attempt at a Solution I tried to write each component separated, but I don't see how to continue, since all...

See, we know that different electrical appliances in our house require different amount current to work .now first if some appliance is working which requires less current then less current will be passing through wires but when we use electrical appliance which uses high current then high...

Why is it that in bulk matter , though molecules are closely packed electrons are no longer attached to individual nuclei It is mentioned in 6th line of 3.3

Hello, It is my understanding that a moving magnetic can induce an electrical current, and that conversely, and electrical current can move a magnet. I believe that this is the basis by which speakers work (changing electric field causes vibration of the magnet that generates the sound)...

what is that causes the current in the wire that has a stepped up voltage * in the transformer , the wire with more coils * to have a lower current ?

Homework Statement Here is the Task: The solar wind streams off of the sun in all directions at Speeds of about 400 km/s. It contains roughly equal number of electrons and Protons. Near the Earth we find in a cube with a side length of 1 m about 8.7 * 10^6 Protons. The velocity of These...

I'm still a beginner at Electricity and electromagnetism, I'm wondering If we connect a wire to a positive terminal ONLY , why won't the electrons flow to the positive terminal of the cell as electrons are negatively charged, I have been days thinking about it and I need a clear convincing...

According to the Gauss law, the extra charges gather on the surface of a conductor. When there is a current in a conducting wire, do the charges only move on the surface of the wire or we have current also inside the wire? If we also have current inside the wire how is it compatible with Gauss law?

Electric current is often analogized to water under pressure in pipes. When water is moving through a pipe, the energy of the system is the potential energy of whatever is giving the water its pressure -- a column of water, say -- and the kinetic energy of the water molecules as they move...

when we electric field between two conductors in certain direction the current density should pass in its direction why current density direction change at boundary although the direction of electric field is the same for both conductors

Theoretically , a change in either electric or magnetic field will cause a current to flow , i am already familiar to Faraday's law of electromagnetic induction , so i tried to search about producing a current using a varying electric field, didn't find anything , i found an interseting...

Homework Statement 86.9g of liquid water at 304K is heated by 1.75A passing through 24.7Ω for 104s what is the final temp Homework Equations its been a while since i did physics so bear with me if i get something mixed up here q=mCs,pΔT q=ItΔψ ψ=pot dif so isn't that just V from...

Let us consider a circuit... There's a 10 V battery... A Rh(resistor with changeable resistance) and another battery is connected in parallel in the circuit... Now current I (due to the 10 V battery) divides into two parts when it reaches the parallel connection... Let's note them by Ir and...

Homework Statement The power rating of an electric appliance is 1500 W. How much current does this appliance draw when it is used in a home electric circuit ( V= 120)? Homework Equations P= VI The Attempt at a Solution P= VI => I= P/V => I= 1500W/120V = 12.5A Is this...

You mostly hear about electrons as being the vehicle of an electric current because we think of wires and metal. However, if an electric current traveled through the human body, it would be in the form of ions, right? But what happens at the interface between body and wire? I am guessing that...

Homework Statement E& M Purcell, 3.11 A 100-pF capacitor is charged to 100 volts. After the charging battery is disconnected, the capacitor is connected in parallel to another capacitor. If the final voltage is 30 volts, what is the capacitance of the second capacitor? How much energy...

I am looking for something that should be relatively simple to find, but as such, I have not been successful. I know that an electric current can be created by moving through a magnetic field. I have found equations that indicate this can be based on the velocity and the length of said object...

hi, why electric current is a SI base unit - why not couloumb?

Hi, all. There's a thought flashing through my mind yesterday. Sorry for my lack of knowledge. The thought must be something wrong. Can anyone correct it? Thanks If there is a 3000000km long power cable, and the cable is pulled to 3000000km away from the earth. A power source connected on...

I recently finished a lab experiment on heating effect of an electric current(heating water by running current through a resistor). I did two runs of the test first at 2 amp and second at 3 amp. The first run shows a small % error however the second run gave me 26% error. What would explain the...

Hello, I am currently trying to create a sculpture that involves having a live electric current running through water inside of a sterilite tub. The way I would like to go about doing this is very crude, I would like to take an extension cord, cut the end off of it,and stick the live end...

ok so here is the question number 45 and its second part and this is what i did I have a c magnet drawn with the north pole and the bottom opening right. And the magnetic field lines running between the two polls (virtically) And I have a conductor running between the poles...

http://en.wikipedia.org/wiki/Coaxial_cable http://en.wikipedia.org/wiki/Poynting_vector Could a coaxial cable be used for electric current instead of radio signals? 'For example, the Poynting vector within the dielectric insulator of a coaxial cable is nearly parallel to the wire axis...

Electric current -- High voltage power lines buzzing Question: High voltage power lines string along roads often give off a faint buzzing sound. Use what you know about the motor principle to explain the source buzzing. ok, so i have no idea how to approach this. I've never heard...

I was just wondering and I looked and couldn't find anything. I suppose i could experiment it my self but anyway. If I had a wire with an electrical current flowing through, just say 10Amp; and I pass a magnet near the wire, would it slow the current down? Or increase the resistance? I know...

I've checked Wikipedia for answers but can't find any. I'm learning electromagnetism in school now. I don't know why this happens and so I can't understand the lessons! Can anyone tell me why? Thx :)

Homework Statement 8. An electric current in a conductor varies with time according to the expression I(t) = 100 sin (120*pi*t), where I is in amperes and t is in seconds. What is the total charge passing a given point in the conductor from t = 0 to t = 1/240 s? Homework Equations...

why electric current flows at speed of light when we know that current is due to the drift velocity of electron which is only few km/s(i think)?

Few years ago, we have known about the phenomenon that Coca cola is overflow severely when a piece of Menthos candy is put inside. I replicate this experiment, with a multimeter is used to measure the current. With my surprise, the needle vibrates to show that an electric current is...

How do you represent a certain mass of plasma (ions and free electrons) traveling inside a containment from point A to point B as "I", electrical current? Trying to make a connection, Doug Ettinger

"An electric conductor carrying electric current from left to right is placed in a downward magnetic field. It is observed that there are positive charge on the front of the conductor and negative charge a the back. If the electric current is reverse, flowing from right to left, then the...

Homework Statement A net charge of 49 mC passes through the cross-sectional area of a wire in 12.0 s (a) What is the current in the wire? _4.1E-3_ A (b) How many electrons pass the cross-sectional area in 1.0 min? ______electrons Homework Equations I=Q/t The Attempt...