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

learn more… | top users | synonyms

2
votes
3answers
19k views

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?
0
votes
0answers
52 views

Is there a way to draw a thermodynamic diagram analogous to an electrical schematic for simple ideal systems?

I have a small system in air (which should be part of the schematic), consisting of several cylinders within one another and contacting ideally at various spots. How do I model it as if it were an ...
0
votes
1answer
41 views
0
votes
2answers
287 views

Why does all the current flow through a short circuit if its voltage drop is considered zero?

Path of least resistance vs. short circuit I know the path of least reisistance has been clarified already However, to derive the equations you need to assume that the voltage of each parallel ...
0
votes
1answer
37 views

magnetising the material using coil

I studied that when alternating current is passed through the coil ,the coil produce magnetic field (primary) as shown in figure,when any conducting material placed near to that field, eddy current ...
6
votes
3answers
8k views

What happens if I throw a battery into water?

Today I have by accident thrown a AAA battery into a bucket of water. I fished it out of the water immediately (within 20 seconds or so) and nothing notable had happened and the battery is still full ...
7
votes
2answers
2k views

Why doesn't the electric field inside a wire in a circuit fall off with distance from the battery?

We studied electric fields due to point charges. The magnitude of these fields decreases with the square of the distance from the point charge. It seems to me that we could treat the positive ...
2
votes
1answer
90 views

Must a universal motor always rotate at the frequency of the AC current?

So here I have a picture of a motor (I think it is a universal motor but I am not sure). My question is if this motor is connected to an A.C. supply, does it have to rotate at the frequency of the ...
3
votes
2answers
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 ...
1
vote
2answers
296 views

Why is the voltage output equal to the voltage drop?

I have a very basic question about measurement of voltage output on some simple circuits. Considering the circuits of the figure: Supposing one wants to measure the voltage output $V_2$, on the ...
0
votes
2answers
35 views

Filament lamp $(V,i)$ behavior between 0 and 1V

I was wondering why the behavior is more "chaotic" at 0~1V when compared to 2V+ (which is when it starts to glow).
0
votes
0answers
61 views

Why does this electrometer works?

I was looking at this electrometer (measure of static field E). The principle is : E moves electrons between the 2 electrodes into the coil and there is a magnetometer inside the coil. This ...
0
votes
3answers
2k views

Potential Difference in a wire with no current

Recently I encountered a circuit problem. Imagine, you have an ordinary circuit with a resistor and a battery($60\,\mathrm{V}$ emf and negligible internal resistance denoted by r) with a switch($S_1$) ...
2
votes
2answers
103 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 ...
0
votes
0answers
24 views

Is there a difference between a ground pin and voltage by an ungrounded plug and just a grouned plug?

I have a cortex dj mixer with an ungrounded plug but with a ground pin (that I don't use for now). But I get a lot of noise if a connect my speakers to this mixer, so maybe I need to ground this ...
0
votes
0answers
48 views

Energy conservation applied to a generator

If a turbine runs with a kinetic energy of some joules, the electricity produced must also have the same power given out, according to the energy conservation law. Now if the electric flux is ...
2
votes
3answers
990 views

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?
-3
votes
1answer
50 views

What holds good? [closed]

If the 1 ohm resistor is replaced by a 0.2 ohm resistor. what will be the current flowing through ? What actually determines it ? the OHM'S LAW or POWER CONSERVATION ?
0
votes
2answers
1k views

What's the difference between a positive and a negative current?

Say I have a wire, and I connect a current source on its left end, and a ground to its right end. Then using my power supply I source a positive current, does this mean that electrons will move from ...
0
votes
1answer
101 views

How to solve difficult resistance puzzles? [closed]

How does one solve really difficult resistance puzzles? These are presented in the form of a diagram with multiple resistances in various combinations. I have done some puzzles by reducing the puzzle ...
0
votes
1answer
37 views

Why a capacitor's potential increase until it is equal to the potential of the battery?

I understand that the potential between the plates of the capacitor increases as the circuit runs, but why it stops increasing exactly when it becomes equal to the potential of the battery?
-1
votes
1answer
22 views

Current and Heat in Circuit [closed]

Find current through the circuit. Also, find heat generated in each resistor. MY ANSWER:- In Parallel, 1/Rp = 1/12 + 1/6 = (1+2)/12 = 4/12 Rp=3 ohm Total Resistance = 4 + 4 ohms = 8 ohms ...
3
votes
3answers
193 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 ...
22
votes
6answers
4k views

Could someone intuitively explain to me Ohm's law?

Could someone intuitively explain to me Ohm's law? I understand what voltage is and how it is the electric potential energy and that it is the integral of the electric field strength etc. I also ...
0
votes
2answers
121 views

What does Potential Difference between a load/resistor mean?

Guys this has been bugging me for ages and all the answers i found online were unsatisfactory. My questions is, what does difference in potential or potential drop after current passes through a ...
1
vote
3answers
485 views

How to Determine and Verify Series and Parallel

I am having a lot of trouble visually identifying which elements in a circuit are in series and parallel is there a formal mathematical way I do this with Kirchoff's Law?
0
votes
2answers
384 views

Current in Inductor and Capacitor with DC voltage source? [closed]

A DC source in series with pure Inductor and pure Capacitor no Resistance. How the current will flow in this circuit? What I just know is that in the beginning Inductor will behave as an open circuit ...
2
votes
6answers
185 views

Current when resistance is 0

A short circuit has $\rm 0$ resistance. We use Ohm's Law $\rm V=IR$. If $\rm R=0$, then $\rm V=0$. Doesn't this mean $\rm I$ can theoretically be anything? Thus $\rm I$ can be like $\rm35A$ for ...
3
votes
1answer
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 ...
0
votes
0answers
125 views

Loaded Quality Factor

I came up with an expression for the reflected power of a resonator: $$\left| \Gamma \right|^2 = 1 - \frac{1-\left(\frac{\kappa - 1}{\kappa + 1}\right)^2}{1 + 4 \left( \frac{Q_U}{(\kappa + 1)} ...
-1
votes
1answer
107 views

How to find power dissipation of bulbs [closed]

The following circuit is connected in series and $240V$ power supply. Bulb $A$ has $240V$, $100W$ rating. Bulb $B$ has $240V$, $500W$ rating. Calculate the power dissipated at bulb $A$ and $B$ ...
3
votes
2answers
245 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 ...
0
votes
0answers
37 views

Physical interpretation of Convolution

Let us say that we are interested in finding the voltage (potential difference) $y$ across the resistor. The circuit consists of a battery, a resistor and an inductor. The problem can be solved by ...
2
votes
1answer
145 views

A working “mechanical” model that explains current in a wire/circuit?

In class we learned about point charges, electrostatic force, voltage, current etc. and discussed circuits along the way. Now problems arise when I try to apply the learned concepts to explain how ...
7
votes
1answer
5k views

How can KVL & KCL be derived from Maxwell equations?

How can KVL (Kirchhoff's Voltage Law) & KCL (Kirchhoff's Current law) be derived from Maxwell equations in lumped circuits? (Lumped network: if $d$ is the largest dimension of the network and ...
3
votes
2answers
342 views

Why is the voltage of a battery equal to the emf?

We know that there is an electric field inside the battery that works against the moving electrons of a circuit. But there is also the chemical force of the battery that at some point become equal. ...
0
votes
0answers
68 views

Is this the reason why a circuit with no components (except wire) would discharge the battery faster?

I read that if I simply connect two ends of a battery it would discharge really quick and it would last longer if the circuit contained e.g. a light bulb. I wondered why is this happening and my ...
4
votes
1answer
133 views

Why can gold be drawn out finer than light?

The metal gold is extremely malleable. Gold is also ductile and one ounce can be drawn into 80 km (50 miles) of thin gold wire (5 microns diameter) to make electrical contacts and bonding wire. I ...
1
vote
2answers
322 views

Having trouble understanding the concept of current and Ohms law

Circuit in series: $10\,\text{V}$ power supply, 2 resistors connected. Each resistor is $10\,\Omega$, total of $20\,\Omega$ resistance. If I put an ammeter at the end of the circuit, will the current ...
1
vote
2answers
97 views

Explanation for: A monopole antenna must contain a resistor (or equivalent) and therefore must have 2 terminals?

Could someone explain why this sentence makes sense: A monopole antenna transfers energy from electrical domain to the electromagnetic domain, hence must contain (equivalently) a resistor, hence ...
-1
votes
2answers
117 views

Battery charging a Capacitor

Ok I know there is a similar question already on here, but mine takes it just a step further. What I would really love to know is exactly how much energy is being transferred from a battery into a ...
1
vote
0answers
52 views

On resonance of an RLC circuit

How do I prove that the width of resonance in an RLC circuit is the inverse of the proper time of the circuit? I know that the amplitude of charge in the condensator is ...
-2
votes
1answer
25 views

Number of electrons flowing in a circuit [closed]

Does the number of electrons flowing in a circuit get affected when we turn on the light? If yes or no, then why. Help please.
0
votes
1answer
2k views

Capacitor charging, work done by battery on changing polarity

A uncharged capacitor $C$ is connected to a battery with potential $V$. It becomes fully charged and has a charge $Q=CV$ stored on it. Now the polarity of the battery is reversed. The capacitor will ...
0
votes
2answers
91 views

how current flows in a parallel circuit as the potential difference is same?

Since we know current can not flow in a wire if there is no potential difference in its two terminals. How current flows in a parallel combination where each load has equal potential difference in ...
1
vote
0answers
51 views

Why can xenon gas stay ionised after the “trigger voltage” is removed?

From my understanding of a Xenon flash circuit, a storage capacitor and a trigger capacitor are charged up to about 240V (both with similar RC values, but less capacitance is needed for the trigger ...
0
votes
1answer
412 views

Question on an unbalanced Wheatstone bridge

Let, P/Q = R/S in the usual sense of a Wheatstone bridge where PQRS are resistances. Then we know that the potential between midpoints of PQ and RS are equal and there's no potential difference ...
1
vote
4answers
1k views

What is the difference between a circuit with a resistor and one without it in energy terms?

In Fundamentals of Physics (HRW), an equation is derived for the current in a circuit in terms of its emf and resistance by the 'Energy method'; that is, deriving $\epsilon = i \cdot r$ and saying ...
12
votes
4answers
3k views

Symmetry in resistor circuits

Given 6 points that are connected with each other with a resistor of resistance $R$, find the resistance between any two points. (Answer: $R/3$) (All the conducting wires have the same ...
0
votes
0answers
35 views

What is ultimate AC frequency and phenomena related to it?

Just as in title. What is the top AC frequency physically possible to obtain? And are there (and if yes, what?) phenomena occuring only at large frequencies? I'm thinking about a metallic wire. I know ...