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

learn more… | top users | synonyms

0
votes
1answer
83 views

Calculate the resistance in serial and parallel circuits

I have a serial and a parallel circuit. In both of the circuits I am using two resistors.These two resistors have the same resistance $a$. In both the circuits I have tried reading the amount of ...
0
votes
4answers
117 views

Current in purely LR DC circuit at t=0

I was told by my professor that the current in a purely LR Circuit with at initial state (JUST after closing the switch) is zero. Can you please help me understand why it that so?
-1
votes
2answers
40 views

Why can't I get a output lower than 0V in this circuit?

In the image above green is my input (node left side capacitor) and blue is my output (node right side of the capacitor). I would expect that the blue sinusoidal looking signal would follow the ...
4
votes
3answers
8k views

Reducing Eddy current losses

Eddy currents are setup in any metallic block which is in the vicinity of changing magnetic fluxes. These primarily cause heat losses, and in certain cases causes damping of the relative motion ...
0
votes
1answer
61 views

How should I interpret the math in showing that the potential difference and the emf in an ideal battery are the same?

I was reading Griffiths' Introduction to Electrodyamics where he says that in order to have the same current through out a circuit there are two force per unit charges acting on the circuit, $f=f_s+E$ ...
1
vote
1answer
65 views

Help me understand static electricity

This is what I understand about electricity: (The following information is paraphrased from the book CODE by Charles Petzold.) Atoms are made up of protons, electrons and neutrons. Protons and ...
1
vote
1answer
262 views

How does a magnetic field produce an electromotive force?

As I keep reading through texts and online, I keep getting conflicting views when in magnetic fields and electromotive forces are involved. From what I can see, the emf is the work done per unit ...
0
votes
0answers
46 views

How does current flow in the circuit during negative cycle of input?

So,as far as I know the input signal just controls the current from +Vcc as per this analogy But in the first picture during the negative half cycle of the input waveform the output wave form is ...
6
votes
6answers
5k views

What is Electromotive force (EMF)? How is it related to potential difference?

What is Electromotive force (EMF)? How is it related to potential difference? Is it the creation of potential difference in any conductor??Is it a process?Why is it called force? Does writing emf ...
1
vote
1answer
136 views

Loading a capacitor in an RC circuit

I have an RC circuit to which I am going to apply voltages of 5V every 100ns. So every 100ns, the capacitor will change its "state" from charging up to uncharging. I have been trying to find the a ...
0
votes
0answers
416 views

Difference between rheostat and potentiometer & How connections are made to a simple rheostat?

I am confused about connecting wires to a rheostat. Can you please name and explain the parts of rheostat? Also how do we know which end of rheostat is to be used in circuits? In the last picture ...
1
vote
0answers
26 views

Equivalency of Q Factor Definitions

The Q factor is defined (seemingly) as $$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}$$ however on Wikipedia is says that the Q factor can be ...
0
votes
0answers
53 views

Electron flow through insulators connected to conductors

I imagine a simple circuit consisting of a power supply and conductor connected to an insulator (heavy resistor in series with wires). In a closed circuit, I understand that the battery's E field ...
1
vote
2answers
1k views

Can we pass electricity through air?

Electricity: I was wondering, whether we can pass electricity through air over a distance of 100 meters or so as electricity means the flow of electrons and we have seen the discharge or movement of ...
0
votes
4answers
154 views

Current and voltage word problem [closed]

If a conductor with a current of 200mA passing through it converts 40 J of electrical energy into heat in 30 seconds, what is the potential drop across the current ? The answer is 6KV, but I don't ...
2
votes
2answers
391 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 ...
1
vote
1answer
50 views

Why isn't this a valid derivation of the formula for capacitors in series?

I had to derive the formula for capacitors (I decided to use m capacitors in my derivation) in series, and this is what I did. The formula for a capacitor is $$Q=CV,$$ which is the same as saying ...
0
votes
1answer
64 views

Thermometric Properties

A thermocouple thermometer with 10 ohms of resistance is calibrated with its hot junction and cold junction immersed in steam and melting ice respectively. An EMF of 5.6mv is measured. This ...
0
votes
0answers
20 views

Is this the creation of an electrical circuit

If I place a aa battery on the negative side and a aa battery on the positive side on to a stainless steel surface and then place a quarter on the other side have I completed an electric circuit? Is ...
0
votes
1answer
194 views

Name of battery voltage when load connected/disconnected

If I had a 3V battery, and when no load connected it reads 3.2V, and with a load 2.8V (just a hypothetical example), what is the name for these two terms, with a load or no load? I know the voltage ...
2
votes
1answer
81 views

Scattering Matrix of a Given Circuit - Microwave

This might be an easy question but I couldn't find it in our course book[Microwave Engineering, Pozar, 4th ed] or on internet. I have a homework and one of the questions asks me to find the S-Matrix ...
1
vote
2answers
45 views

What dynamical system could this $\dot y = \alpha(y-\lambda), y\geq \lambda$ equation describe?

Just out of curiosity, can anyone identify electrical, mechanical, chemical, etc process that is governed by a differential equation of the form $$\dot y = \alpha(y-\lambda), y\geq \lambda$$ where ...
0
votes
1answer
71 views

Load resistance adding with minimized power and voltage constraint [closed]

Consider the simple circuit below: Suppose $V$ and $R$ have set voltage and resistance values respectively, and you are to choose the resistance values for $R_1$ and $R_2$. However, you must choose ...
0
votes
1answer
30 views

Showing $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} \frac{R_1}{R_1+R_2}$ [closed]

Consider a voltage divider with $V_{out}=V_{in} \frac{R_2}{R_1+R_2}$. Show that for a small change in $R_2$, the voltage divider equation is: $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} ...
1
vote
3answers
358 views

Defining Reference Directions for Voltage and Power (sign convention)

My professor decided to use the above reference directions when calculating power in circuits. He says that when power > 0, power is consumed. When p < 0, power is generated. This definition is ...
0
votes
0answers
47 views

Probe/Sensor-design for pulsed electromagnetic field

So I have a wire/coil, acting as a sender, which has a pulsed signal as described below. I would like to build a sensor/probe that can detect the electric field at a distance, where the primary goal ...
0
votes
1answer
114 views

Electrical Analog of a Chain of Springs

I'm trying to wrap my head around the Force $\rightarrow$ Voltage analogy between mechanical and electrical systems. I have a mechanical system where masses are connected by springs in series, and ...
3
votes
3answers
614 views

The role of resistor in e.g. an AND gate

What is the role of the resistor in e.g. an AND gate like this one? : One often sees lots of resistors in electric circuits, but I haven't really understood their role.
3
votes
3answers
6k views

Why does the current stay the same in a circuit?

I was informed that in a circuit, the current will stay the same, and this is why the lightbulbs will light up (because in order for the current to stay the same, the drift speed of the electrons need ...
4
votes
2answers
2k views

Why is the voltage drop across an ideal wire zero?

I'm having trouble conceptualizing why the voltage drop between two points of an ideal wire (i.e. no resistance) is $0~V$. Using Ohm's Law, the equation is such: $$ V = IR \\ V = I(0~\Omega) \\ V = ...
0
votes
1answer
74 views

Dependence of the Capacitance on the Material and Geometry of the Plates

I have two questions concerning capacitors: 1) We know that the capacitance of a capacitor also depend on the dielectric material inside as $C=$ $\dfrac{K \epsilon_0 A}{d}$ But what if the ...
1
vote
4answers
113 views

Measuring electric conductivity

My daughter is doing a science experiment on which metal (e.g., copper, silver, aluminum, iron) has maximum electric conductivity. We are assuming we can accomplish this by using different metal, 3 to ...
0
votes
3answers
323 views

Why is emf equal to PD when circuit is “open”?

I understand that the set up of a battery consists of very good, but not ideal conductor, and therefore, some internal resistance exists. Also, I get that emf is the PD that would exist if the ...
1
vote
2answers
28 views

Determining the behavior of the transference function as $\omega\to 0$ or $\omega\to\infty$

I'm studying experimental Physics and one of the experiments I must understand is about electronics concerning filters. Considering one RLC filter, measuring the output at the resistor we have the ...
0
votes
3answers
83 views

Current in an RC Circuit

If an $emf$ leaves from point A, the concepts at play in the following diagram are straightforward: at any time, the $I_{R}$ = $I_{c}$ as time increases, $\Delta V$ across $R$ decreases and it ...
0
votes
1answer
656 views

Circuit breaker Trips during thunderstorm

The circuit breaker at the electrical mains trips at home when there is a thunderstorm outside. Why does this occur?
3
votes
2answers
2k views

How are the CPU power and temperature caculated/estimated?

From Wikipedia The power consumed by a CPU, is approximately proportional to CPU frequency, and to the square of the CPU voltage: $$ P = C V^2 f $$ (where C is capacitance, f is ...
0
votes
2answers
57 views

Isn't the inductor equation negative?

The inductor "resists" change in current. So say you measure the voltage across the inductor from point A to point B - the current is flowing in from A towards B. Now say the current is increasing. ...
1
vote
1answer
44 views

Is it true that a processor with a higher temperature uses inevitably more power in comparison with a processor with a lower temperature?

If a processor has a higher temperature, can you be sure it it consumes more power than a processor with a lower temperature? And is the reverse relationship true? A processorchip with a higher mean ...
0
votes
1answer
124 views

Voltage calculation and reference voltage in simple linear circuit [closed]

For the diagram above, the following voltages are specified: $V_A = 4V$ $V_D = 2V$ $V_a = 0V$ Here, $V_{ab}$ indicates the voltage referenced from node b to node a. In other ...
0
votes
1answer
125 views

Direction of Current Flow in Complex Circuit

Physics Hypertextbook writes that "The current through the 1 Ω resistor most certainly runs from right to left." Why is that true? My approach: I arbitrarily assigned a counterclockwise ...
1
vote
1answer
52 views

Where are the negligible and infinite resistances, respectively, of the ideal am- and voltmeter?

Consider the picture below. An ammeter is shown to the left, a voltmeter to the right. They consist of a d'Arsonval galvanometer, which is a coil (with a pointer attached) that can rotate in a ...
1
vote
2answers
190 views

Why is the current in an electric circuit constant?

Considering electrostatics, suppose we have two charges of equal value and opposite sign and we put electrons along the road between them: We know that the electrical force or field is different from ...
1
vote
1answer
66 views

Drift velocity of charges in current

In an electric curcuit, charges (electrons e.g.) move randomly around very, very fast. When a current is set in a curcuit, the charges still move randomly, but have a drift velocity around the ...
10
votes
2answers
3k views

Where does electricity go from a solar panel that is not plugged in to anything?

I found a similar question here on this site, but my question is slightly different. If a solar panel is exposed to sunlight but is not plugged in to anything--dc load, inverter, etc--where does that ...
1
vote
1answer
81 views

Why is there current in LC Circuits?

When we connect two electric sources (positive to positive and negative to negative) then the current that runs the circuit is calculated as follows: $ I = (E1-E2)/(2r + R) $ In case of an LC ...
6
votes
0answers
63 views

Weird phenomenon on aluminum laptop casing [duplicate]

A couple of days ago I observed a phenomenon which I'm not sure I understand correctly. My brother-in-law has recently bought an ASUS gaming laptop in an aluminum casing. When the power supply is ...
1
vote
3answers
3k views

Magnitude of magnetic field at the center of circular wire

I'm preparing for an exam by solving the sample questions , here is the one I'm having difficulty with : Following is the given circuit. Which contains two resistance $R_1$ and $R_2$ in form of ...
0
votes
1answer
106 views

Variable Resistance

We know that the resistance increase with temperature or for exemple in an AC circuit, the resistance is superior to the same resistor for DC current due to skin effect. But my question is for a same ...
3
votes
4answers
265 views

Birds and cables: how is the potential difference between two diff. cables established?

The common explanation of why birds don't receive a shock when standing on high tension cables is that there needs to be a considerable potential difference between both of his feet for him to receive ...