An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.

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Why are ammeters used in series and voltmeters in parallel?

As I'm reading a course on electricity, this one says that an ammeter should be branched inline and not on a bridge. Can someone explain to me physically why we branch a amperemeter inline and a ...
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515 views

How can there be current if all paths have same potential difference

I am learning about circuit analysis now, but there is something that I can't wrap my head around. Imagine this simple circuit: ...
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Measuring human resistance with a DMM

When I attach a Digital Multimeter (DMM) to read the resistance between my right and left hands, the resistance starts off high and reduces over time. It appears almost like "RC-type" behavior. Can ...
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9k views

Ohmic and Non-Ohmic devices

Why do some conductors follow Ohm's law and some do not? Isn't there any universal law that can explain the flow of current?
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150 views

What happens in circuits where the propagation time of the electric field is significant?

Kirchhoff's current law assumes "that whenever current flows into one end of a conductor it immediately flows out the other end". I want to understand what happens when we cannot make this ...
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66 views

Parallel resistances

How is the net resistance lesser than the least resistance when resistances are connected in parallel? The electrons will have to flow through one of the resistances, right? To me, it seems like the ...
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36 views

Detect Breaks in Mesh Circuits [closed]

PS: I will mess up a lot of terminology throughout the question. Anyways, I want to build a circuit which is in the shape of a mesh, something like a table and subsequently detect whenever there is ...
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Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
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166 views

Voltage in a circuit?

The voltage of the battery signifies the difference in voltage between the positive and negative terminal What does this mean? The definition of voltage difference I'm familiar with is the amount ...
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3k views

Round bulb and Long bulb in Series Circuit

If you have a series circuit with a battery, one round bulb (with thicker filament), and one long bulb (with thinner filament), the round bulb does not light up and only the long bulb lights up. ...
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289 views

Electric circuit. Slight problem with the sign on voltages

Translation first! The figure shows an electric circuit. a) Use Kirchhoffs 2.law on the part-circuit abed and show that $I_3$ = 0,50A. b) Explain that $I_2 + I_5 = 2,0A$. Use Kirchhoffs 2.law on the ...
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80 views

Why do some people support more electricity than others?

There is a game where people hold by their hands and two of them touch the electrodes of a shock box, then an electric current flows through them. I understand that since they are all making a single ...
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81 views

How does the energy remain conserved in a transformer?

The induced voltage in the secondary coil of a transformer is given as $\frac { { N }_{ S } }{ { N }_{ P } } *{ V }_{ P }$ (where ${ N }_{ P}$ and ${ N }_{ S }$ are the number of turns in the primary ...
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37 views

Does the internal resistance of a battery dissipate heat as expected?

A common real battery is often modelled (to a good approximation) as a perfect voltage source having emf $\varepsilon$ with a series internal resistance $r$. So, when a current $I$ is drained from it, ...
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127 views

Why does energy flow between a high voltage transmission line and linemen approaching it on a helicopter?

The video High power line workers shows linemen servicing a live high voltage transmission line. As the helicopter approaches the line, the lineman reaches out with a metallic wand that is ...
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122 views

Effective resistance across 2 adjacent vertices of a dodecahedron with each edge $r$

What will be the effective resistance across 2 adjacent vertices of a regular dodecahedron (12 faces) with each edge having resistance $r$? Here is the source for the problem, it's problem 20. on ...
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197 views

$\vec{E}$-and $\vec{B}$-fields in RCL circuit

Consider a basic RCL-Circuit consisting of an ideal resistor, an ideal capacitor and an ideal inductor in series. Assume that at time $t = 0$ the current is zero and the capacitor is charged with ...
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313 views

How does an inductor store magnetic energy?

I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
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296 views

How to model “Doppler Distortion” of speakers?

Simple Model w/o Doppler I have a speaker driven by an electrical signal. The pressure at the sampling point is some linear operator acting on the input signal: $L[ s(t)]$. Where $L$ combines the ...
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170 views

Is there a differential equation that can represent a circuit with an arbitrary voltage source connected acrorss an antenna?

An RLC circuit with a voltage source can be characterized by the differential equation: $$ LC\;\ddot{I}\left(t\right) + RC\; \dot{I}\left(t\right) + I\left(t\right)-C \;\dot{V}\left(t\right) = 0 $$ ......
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78 views

Direct current and metallic conduction

Suppose we have a circuit with and EMF source and a resistor. We know that when electron moves from one terminal of a voltage source to another it encounters resistance, which is basically collisions ...
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828 views

Flow of electrons in a circuit

When the electrons flow in a circuit, so are those the electrons from the battery or are those the electrons of conductor like copper wire, etc..which are flowing in the circuit?
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810 views

Explanation of the Graetz circuit

My knowledge of circuits is pretty rudimentary and I've never really understood circuits, so I'm having trouble with the concept of Graetz circuits: When you register the voltage on the resistor R ...
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7k views

Effective resistance of inductor

In a lab experiment, we connected a simple circuit: an AC voltage source, connected (in series) to a variable resistor and an inductor. We measured the current in the circuit, and the voltage that ...
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135 views

If current takes the path of least resistance, why do parallel circuits work? [duplicate]

Why doesn't all the current flow down the path with the weaker resistance instead of dividing and going through both resistors (in a parallel setup with 2 unequal resistors)?
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806 views

Why do high voltage transmission line workers need a Faraday cage suit?

In this video the high voltage transmission line workers are wearing a Faraday cage suit. Why is this needed? Without the Faraday cage, the resistance of the human would be very high compared to the ...
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420 views

Why is there no induced electric field in the experiment (Faraday's Law)

Below are three circuit diagrams for each of Faraday's experiments that allowed Faraday to come up with Faraday's Law. In Griffiths' Introduction to Electrodynamics Griffiths states (on page 302 of ...
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540 views

Resonance Frequency of High Resistance RLC

I was measuring the resonance frequency of an RLC (all in series) circuit using an oscilloscope and a function generator. Now resonance frequency is given by: $$f_r = \frac{1}{2 \pi \sqrt{LC}}$$ In ...
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49 views

Can a transformer transfer all power?

How can the transformer transfer exact power from primary winding to secondary winding if there are core losses, eddy current losses and hysteresis losses?
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256 views

RLC circuit, turning off the voltage source

An RLC circuit (pictured above) is governed by two equations: \begin{align} -iR &= -L \frac{dj}{dt} = \frac{q}{C}+V(t) \\ \frac{dq}{dt} &= i+j \, . \end{align} $q$ satisfies the equation $$\...
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Delta to Star/Y Conversions and vice versa in Electric Ciruits

We all know the basic rules for conversion of $"Delta"$ circuits to $"Star"$ circuits and vice versa. We also know that this is needed for simplification of circuits in complex cases. Can anyone ...
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889 views

What is the current through the lamp?

We have the following circuit: A neon lamp and a inductor are connected in parallel to a battery of 1.5 $V$. The inductor has a 1000 loops, a length of $5.0 cm$, an area of $12cm^2$ and a ...
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591 views

Instantaneous current after battery unplugged in RL circuit?

I've been racking my brain over this, and I can't find any clues in my textbook as to how to approach it. I have the following circuit: My goal is to find R such that, right after the switch is ...
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756 views

Compute closed line integral of electric field in circuit

I have a circuit where resistor is parallel to capacitor, which is charged with voltage U. How to compute line integral around closed loop to get the result of Kirchhof second law - $U_{capacitor}+I\...
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811 views

Electrostatic notion of voltage as it applies to circuits

I have a question that's been bothering me about electric fields, voltage, and circuit analysis. Initially, I came to understand voltage as it was taught in the context of electrostatics - through ...
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324 views

How are quantum potential wells fabricated?

Potential wells, such as infinite and finite potential well, have been the standard examples in quantum mechanics textbooks for tens of years. They started being only theoretical toy models but as ...
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166 views

How to calculate the resistance of a resistors in a grid?

I've found a lot of example of a grid where you want to total resistance of a grid. My problem is different. Let's say you got a grid of resistance (3x3) but you only have the total resistance between ...
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Can a magnetic lock be negated or overcome by a stronger electro magnet? [closed]

Magnetic locks seem to be fairly standard on modern buildings. Is it, though, possible to negate a magnetic lock my placing an oppositely-polarized, strong electromagnet across from the magnets on the ...
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38 views

Tesla Coil stops sparking until restart [closed]

I have a tesla coil with NT-1530-OUT Transformer, 23 turns (max) primary, 1m secondary(~1600turns), with MMC and rotary sparkgap. Gets 50cm sparks but try to tune the tesla coil by shifting top load,...
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Is voltage difference always proportional to its derivative?

We write, because of Ohm's law: $$V=RI(t),$$ but also we have $$C\frac{dV}{dt}=I(t).$$ From the first equation we deduce that $V\propto I$ and from the second $\dot V\propto I$. So we can conclude $$...
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571 views

Olympiad physics 1996 problem [closed]

I don't understand the official solution of the first problem of the 1996 International Physics Olympiad. They give this circuit: Each black box is a resistor of resistance $1\Omega$. They then ...
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4answers
438 views

Justification of root mean square [duplicate]

In the top answer to the question Why do we use Root Mean Square (RMS) values when talking about AC voltage, the following was stated: This RMS is a mathematical quantity (used in many math fields)...
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3answers
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Is there inductance to a DC circuit?

When a DC circuit is carrying current, large amounts or small, is there induced-emf due to the inductance? Or is it only applied to AC circuits?
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Current Through a Circuit with an 8 Resistor Setup

The following is a question from a practice Physics GRE exam (found online at ETS's website). The circuit shown in the figure consists of eight resistors, each with resistance R, and a battery ...
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453 views

Is equivalent resistance always lower if we add a resistor to a passive electronic circuit?

How to prove that equivalent resistance of any passive network is always lower if we add a resistor between arbitrary two nodes? Note that this is not necessarily a parallel circuit, 2 nodes that we ...
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4answers
163 views

Why current loses its energy?

Can someone explain or give a link to explanation why current looses its energy? For example in simple circuit with lamp. I understand that the energy is spent for heating and lighting. But how ...
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2answers
108 views

Why is an $LC$ oscillator lossless, but $C V^2 / 2$ energy is lost to a capacitor connected to an ideal voltage source?

It is mathematically proven that in an $LC$ oscillation that all the energy gets transferred from the inductor to the capacitor and vice versa. There is no energy loss as there is no load in the ...
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Current from induced emf

If the induced emf in a circuit is negative, and current from this emf is the emf over the resistance, what happens to the negative sign in the induced emf when solving for the current? Surely there's ...
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Can Kirchhoff laws be applied to any circuit?

Kirchhoff's loop/current rule is just law of conservation of energy and Kirchhoff's junction rule is just law of conservation of charge.So, I think that these can be applied to any circuits unlike Ohm'...
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Why do current-carrying wires heat up?

Obviously wires heat up too, but why do they heat up? And for the same reason, why do we get electrical burns?