Tagged Questions

A measure of the rate at which electric charge is transported (especially through a circuit), it has units of charge/time.

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Can charge flow to a neutral body?

If an electrically positive object is kept with a neutral object, in which direction will charge flow? Will charge flow from positive to neutral until both have equal charges, or will nothing happen ...
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Does a capacitor experience a Newtonian reaction when being charged?

Say I have a capacitor that is being charged with a battery. There are two wires, one on the positive and one on negative terminal of the battery which go to a capacitor. During the charging, a ...
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Short circuit due to loose terminations

I have been reading into wiring and circuits and found someone post that they had a circuit breaker tripping because of a loose wire in the circuit. They claimed the hot screw/lug combination ...
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Ohm's law experiment

I was going through my physics laboratory manual. In the Ohm's Law Experiment, the book states a few precautions without any reasoning. 1.The wire whose resistance has to be determined should ...
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Half deflection in a galvanometer [on hold]

Why is half deflection taken while measuring the resistance of a galvanometer? Can't we take deflection in other ratios? Please help. I meant to ask while taking out the shunt resistance, why do we ...
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How can “…electrons flow in metals, but not in the ground…” explain grounding rods?

I really enjoyed Why is the charge naming convention wrong? But, in the comments at the very end, the statement that "...electrons flow in metals, but not in the ground..." left me uneasy. I was ...
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Why is power dissipated in a circuit maximum when external resistance is equal to the internal resistance in the circuit? [closed]

[![question 24][1]][1]Suppose in a circuit the battery has emf 6V and internal resistance 3ohm. It is connected to an external resistance = R ohm. According to my ...
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If we increase dimensions of a wire, how does electron density change?

If we increase the diameter of a wire, does the electron density change at all? When we increase the diameter or the length of a wire (while solving numericals) do we add appropriate number of ...
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How to apply kirchoff's laws to motors in DC and AC settings

DC case: is it ok to treat a motor as a variable resistor, with resistance depending on the load? AC case: suppose I have a motor that runs at 120V AC and is rated to X watts, how can I determine how ...
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Some questions related to circuits and flow of electrons

I have some doubts related to electric fields and flow of current. So, let us assume an electric circuit, which contains a battery and a wire connecting positive and negative terminal of the battery. ...
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What is meant by “current” in this context?

This is a quote from Optics by Hecht: A stationary charge has a constant E-field, no B-field, and hence produces no radiation—where would the energy come from if it did? A uniformly moving ...
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Why can't we use Meterbridge to measure high resistance and low resistance?

Our physics master taught us that we can't use meterbridge to measure low resistance but he didn't give a valid reason for that.
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(boundary conditions) Interface between two lossless media

I'm wondering why there's usually no free charges nor free currents in the interface between two lossless media? no free current "I guess" is due to the insulating nature of a lossless media but why ...
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Force Exerting on a magnetic train

A question is already asked ( How does this “simple” electric train work? ). But I've got a question about it. In order to calculate the force which is being exerted on the system including magnets ...
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How do electrons choose their way through nodes? [duplicate]

Suppose I have a circuit, powered by some emf ($V$). If I put two resistors $R1$ and $R2$ of different resistances in parallel, the current at the node is divided following Kirchhoff's circuit laws. ...
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induced current in loop

I'm re-asking this question that was posted by @zhzh and subsequently closed. If you have a loop that is spun clockwise as a magnet is moved near it, is a current induced in that loop? If the ...
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If steady current flows in a metallic conductor of non uniform cross section area then why is current constant? [duplicate]

If area is not uniform then how can current be constant? What happens to current density, electric field, drift speed? Are they constant?
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Electric field due to a current carrying loop

I want to know how I can calculate the radiated electric field in the far zone of the loop. Knowing that the loop is in center at the origin of a x-y plane Knowing that the loop as a time-harmonic ...
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Why does current density changes but not current? [closed]

let us assume that we have a conductor with a specified resistance ( case 1 ) and a normal conductor ( case 2 ) as shown in the figure , and now we apply an external electric field with a battery on ...
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Electric field along a wire and load

I have referred to many books and all of them apply loss in potential across a resistor only in case of circuits. However, the electric field is present in the whole conductor. Hence the electrons ...
58 views

Electro magnetic Wave? [duplicate]

I understand the fact that a static charge produces an electric field around it. I accept the fact(without questioning) that a moving charge produces a magnetic field. Question 1 : If a moving ...
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Why is current shared in a parallel circuit but not a series circuit?

Electricity test coming up. It's not clear to me why current is shared in a parallel circuit but not a series circuit.
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If we consider the electric field to act upon charges with a force, how does it stay in line with Newton's laws?

This should be a relatively simple question. Let's say we have a constant electric field $\textbf{E}$ in a conductor. The electric current density would then be $$\textbf{j}=\rho \textbf{v}$$ where ...
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Why is there no induced current in this loop? [closed]

This problem comes from Barron's SAT Subject Test Physics book. A loop of wire and a bar magnet are moving relative to one another. Which motion in the diagrams shown below will NOT induce a ...
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Semi conductors (holes and electrons)

The following relation is mentioned in my text book for semiconductors in thermal equilibrium. $$n_e ×n_h = n_i^2$$ $n_e$ stands for the number of electrons. $n_h$ stands for the number of holes. ...
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Modeling the working of a transformer by pushing magnet into a coil

Let me go step-by-step. First I will outline a simple transformer. There are two circuits next to each other (not touching). One is an electromagnet set-up (with AC supply) and the other has a ...
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Will moving a magnet through cupped hands change the nerve signals through the hand?

Basically nerve signals are electric impulses travelling from the brain to body parts. What would happen if we move a magnet through cupped hands. Would it somehow interfere with the current of the ...
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Is the electric field in the wires of the parallel circuit always the same and how that affects current?

When we connect two resistors connected in parallel with a battery, it creates an electric field through this wire. well, my question here: Is the electric field in the main wire is the same as the ...
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Voltage and Current

I know that as voltage increases, current increases by $V=IR$, but I really find some difficulty in understanding this at the atomic level (what happens with the electrons inside that wire). I ...
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Magnetic field outside the solenoid

I found solution to problem 257 from "300 Creative Physics problems" hard to understand. In that problem we have very long solenoid with coil wounded in one layer. Data such as: density of turns, ...
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Current from Middle Battery in a Two-looped Circuit

With this question, as with many tutorials of similar questions I’ve found online, my textbook only mentions three currents: $I_1$, which flows through the left loop from and to the 19 V battery, ...
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Does current in a part of a wire create magnetic field at any other part of the same wire?

Let there be a circular-shaped wire - a ring in which there exists a steady current. It creates magnetic field around the wire. This can be evaluated by Biot-Savart Law. As shown in the fig., ...
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Measure a current from a charged surface caused by charge separation

I have separated a charge in an electric field like here (http://elektroniktutor.oszkim.de/grundlagen/gr_pict/coulomb5.gif) and I put the metal out of the field. The charge density on the surface of ...
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Current through resistors crossing each other [closed]

Calculate the current shown by the ammeter A in the given circuit. I've searched the internet but didn't know how to search for it. Please help
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Voltage and Current in an Electromagnet

I'm having a little bit of trouble with electromagnets. I know that a magnetic field is induced by current flowing through a conductor, but what role does voltage play? Does it have an effect on the ...
26 views

Representation of AC through vector

Is there any difference if we use rms value or peak value of sinusoidal wave of AC in phasor (vector representation)? i.e for the length of vector we are allowed to chose one of these,is there any ...
14 views

Angular current in torus

I'm trying to find the magnetic field due to a torus anywhere in space. I'm approximating it as a circular current loop. What I'm having a hard time with is the current in the theta direction, that ...
37 views

What were the experiments performed that lead to ohm's Law

How was the relationship of $V=IR$ first developed? What were the experiments that were preformed that lead to Ohm's Law? I understand that they had devices during George Ohm's time to measure current ...
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Finding the force between parallel currents using the formula of magnetic pressure

Let there be two parallel current-carrying infinitely-long wires separated by $d$ carrying currents $i_1$ & $i_2$ respectively in the same direction. In order to find the force on an ...
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Can we think that an ideal conductor is a friction less space for electrons since under influence of electric field they create an exactly opposing field and produce shielding effect ?If so then how ...
21 views

Resistance used to get maximum illumination with proper security

In which way a resistance is to be connected with a bulb labelled 120V-60W when it is connected with 220V DC source so that maximum illumination with proper security is maintained? What is the ...
35 views

Current and misplaced switch [closed]

I know this is a very noob question, but i just can't help it. Anyways,here is pretty simple circuit Now after the circuit is changed this way, why is the current going to be infinitely high?? I ...
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How can a sheet carrying current get affected by its own magnetic field?

I was reading ' Change in B at a current sheet ' in Electricity & Magnetism by Edward M Purcell. this is the concerned excerpt: Consider a square portion of the sheet, $1~\text{m}$ on a side. ...
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Current in a short circuit [duplicate]

Well,if theoretically we say the value of a resistor is zero then will there be any heat dissipation across the resistor(because heat is produced only when there's a resistance to the flow of ...
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Will current flow entirely through zero resistance if possible to do so?

I am trying to understand how current splits at nodes. I know that if two paths are available, each with R > 0, a current divider is used to find the split ratio. But what if one of the paths has R = ...
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Finding the magnetic field of an arbitrary arrangement of current-carrying wires

For an arbitrary arrangement of current-carrying wire, I am trying to show that the Taylor expansion around $\vec{r} =0$ of a magnetic field $\vec{B}(\vec{r})$ is given by \begin{align} ...
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How could a current passing through a resistance create a voltage as predicted by Ohm's Law?

I have a question about the classic relation $V = RI.$ I know that is the voltage that creates the electrostatic force. But I do not understand how, in a circuit with just a current source and a ...
21 views

Electrons and ionization in an electric current [closed]

Conductors have free electrons to roam, but is that equivalent to continuous ionization of atoms in a conductor, say when an electric current is running through?
How do you prove that the torque acting on an irregular current carrying loop in an uniform magnetic field in the plane of loop = $I \vec{A} \times \vec{B}$ Where, $\vec{A}$ = Area vector of the ...
Figure(a): When a conductor moving inside magnetic field, of a given length at a certain velocity the induced EMF is: $$\epsilon = vBL$$ However, what if we changed the position where the bottom ...