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

learn more… | top users | synonyms

3
votes
2answers
1k 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
52 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. ...
0
votes
2answers
54 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 ...
1
vote
1answer
38 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
65 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
48 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
35 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 ...
2
votes
3answers
89 views

The electric field in wires in a circuit

I have a hard time really understanding the electric field in a complete curcuit. How is the electric field maintained throughout the wiring / the conductors from component to component? The charges ...
1
vote
2answers
87 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
25 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
2k 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
45 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 ...
0
votes
0answers
98 views

How to apply Faraday's law to LC circuit?

I am having problem on using Faraday's law correctly. When I try to apply Faraday's law to the LC circuit: Assume the top plate of capacitor is positively charged and bottom is negative. So no ...
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
42 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
203 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 ...
-1
votes
4answers
98 views

Determine which circuits are parallel and which are in series

I need to find the Equivalent Resistance across A and B. The problem is, I don't know which one's are in series and which ones are in parallel. How do I identify which ones are parallel or series?
2
votes
2answers
319 views

Potential difference with an inductor

As far as I know, the potential difference between two points is defined as the negative line integral of electric field between those 2 points: $$\Delta V=-\int d \ell\cdot\mathbf E$$ I also know ...
-1
votes
1answer
103 views

What happens when a wire is conneceted to a plug point directly?

I did it in my school lab and at first nothing happened. Then I jiggled around, sparks flew out with a small explosive sound. It was really cool. The wire ends got burnt and the holes of the plug ...
-4
votes
3answers
6k views

Why current through all the resistors in series is considered to be same? [duplicate]

Consider the circuit shown, where $R_{1} > R_{2}$. I meant to say that resistance offered by the resistor 1 is greater than the resistance offered by the resistor 2. Keep $t$ constant i,e ...
0
votes
1answer
62 views

Does reflected light change LED power consumption?

If I enclose an LED in "tin foil" so that the photons it gives off are reflected back to it, would the power consumed by the LED go down?
1
vote
0answers
48 views

Solve symmetric circuits by a glance [closed]

How to know with just a cursory glance that the Voltage needed is zero ? i think there must be a way to know it , by symmetry or something
1
vote
1answer
43 views

Where can I get fluidics components?

Many years ago people were interested in developing fluidic circuits, i.e. circuits that are analogous to electric ones but that use fluids rather than electricity. It used to be possible to buy ...
0
votes
1answer
56 views

I wnt to know HOW to create TM, TE, and TEM waves; and is it being used in industry? [closed]

Transverse Magnetic (TM) and Transverse Electric (TE) modes So I'm wholly ignorant of any knowledge surrounding these modes, so bear with me here.. One component is infinitesimally small in the ...
0
votes
1answer
23 views

portable transistor radio [closed]

I recently bought a cheap (@ US$7) transistor radio, with an FM band, an AM band, 4 SW bands, and 2 VHF (tv audio) bands covering channels 1 to 13. However, i later discovered that i couldn't tune in ...
5
votes
3answers
402 views

How is Kirchhoff's voltage law understood in the water flow analogy?

I met the Kirchhoff circuit laws in the past, but now I'm trying to associate them with a practical representation to be sure to understand them. Let's start with the Kirchhoff current law: If I say ...
0
votes
1answer
29 views

Formulas which describe Electric power loss accurate

What formulas describe the real power loss in conductors the best? I heard that there are different effects, like skin effect etc. I want to calculate the % the power drops per meter distance. ...
-1
votes
5answers
5k views

Finding equivalent resistance in complex circuit

In my previous Phys.SE question, situated here, I asked about finding the equivalent resistance of the following circuit : I got some very good answers and some tips. Now what if the same circuit is ...
0
votes
2answers
35 views

Physical Explanation of the steady state in RC circuits

Given a simple RC circuit with a resistance $R$ connected to a capacitor $C$, the differential equation that describes the voltage is $$C \dot V + V/R = 0$$ whose solution is $$V= V(t) = V_0 ...
4
votes
3answers
2k views

Pn junction voltage drop?

This image from wikipedia, explains that there occurs a potential drop across a pn semiconductor junction, and an electric field confined to the depletion region. I already know the reason for the ...
0
votes
2answers
47 views

Power transmission loss in a large circuit

This is a followup question to this question Consider a large circuit like the german electric power transmission network. You have a lot of of people consuming power and a lot of power stations ...
0
votes
2answers
46 views

Kirchoff's loop law

Can any one provide me with mathematical proof of kirchoff's loop law? I am not able to understand from where to start.
0
votes
1answer
53 views

Comparing voltages of Parallel and Series circuits

There are two electric circuits. Resistor 1 ($R_1$) connected with resistor 2 ($R_2$) by series circuit $R_1$ connected with $R_2$ in parallel Each of the circuit has battery with emf and the ...
0
votes
1answer
53 views

Quadrupling Power in a Circuit

If I have a heating wire with resistance $R$ to be connected across a constant potential difference $V$, it would seem like cutting the wire into two (thus each having half the resistance) and ...
0
votes
1answer
32 views

Current in Parallel Circuits

For the parallel circuit below: Why is the current across the ammeter unchanged when the resistance of the variable resistor is increased? I've always learnt that current varies in parallel and ...
0
votes
0answers
33 views

capacitors - Square circuit of two capacitors charging in a changing magnetic field

I've been studying capacitors and DC circuits, and I received this question as part of my homework: The above circuit is a square circuit with side a. E and F are the midpoints of AB and CD ...
9
votes
2answers
2k views

How does my hand amplify an FM radio signal?

I have a gizmo that broadcasts an FM radio signal from my phone's headphone socket to my car's radio antenna. Sometimes, there's another station on the same frequency with a stronger signal and my ...
5
votes
4answers
7k views

is it possible to flow current in open circuit?

First , i don't know much about chemistry and physics. I'm just a graphic designer but i have this question in my mind. I'm sorry if this question is too basic and use 'generic' language. As i know ...
2
votes
2answers
797 views

Is the standard explanation for the ring launcher incomplete?

Related: Faraday's law in a ring The ring launcher is a standard introductory physics demonstration that I assume almost everyone has seen (if not, YouTube it). The explanation of why the ring is ...
1
vote
3answers
88 views

Is there charge build up before a resistor?

I understand that Kirchhoff's current law says that the current, $I$, is constant throughout a resistor, i.e. there is no build up of charge in a resistor. All charge going in to the resistor is the ...
1
vote
1answer
57 views

Exact Relation between voltage and current [duplicate]

I apologize before hand if this seems too naive. I'm having a really tough time understanding the relation between voltage and current. I read that 1 Volt is the amount of work done to move a $1As$ ...
2
votes
2answers
106 views

Is a Thomson's lamp physically realistic? [closed]

The Thomson's lamp is a philosophical puzzle that can be describe as follows: Consider a lamp with a toggle switch. Flicking the switch once turns the lamp on. Another flick will turn the lamp off. ...
0
votes
2answers
36 views

Power in a circuit why is V constant

In deriving the power of a circuit we can do the following: $$\text{P}=\frac{dw}{dt}=\frac{dQ}{dt}\frac{dw}{dQ}=\text{IV}$$ But this assumes that $V$ (since $w=VQ$) is a constant. Why can we assume ...
2
votes
1answer
44 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?
1
vote
1answer
157 views

Question on Shockley's equation for FETs

I'm currently studying FETs (Field Effect Transistors) in Navy school. What I know so far is that in FETs, $V_{gs}$ is reversed biased, creating a depletion zone. What this means in plain English is ...
0
votes
1answer
422 views

Draw a Schematic Diagram of Ammeter Connected in Parallel to explain difference between the diagram of a parallel and series connection

I know that voltmeters are commonly in parallel and ammeters are commonly in series. I believe that the voltmeters in diagrams 2 are actually in series. How am I wrong? ![For example][1] In Diagram ...
0
votes
6answers
12k views

Power dissipated in Series versus Parallel

Do two resistors in parallel dissipate more heat per unit time for an applied voltage when compared to two resistors in series?
0
votes
1answer
45 views

Potential Difference of a wire?

Imagine a circuit with only a 12 Volts battery and a wire connecting the ends of the battery. Point A and point B lies on the wire. What is then the potential difference between point A and B if the ...
4
votes
1answer
174 views

“Bump and Go” toy car mechanism [closed]

Can anyone please explain how the bump-and-go mechanism works in "old-school" toy cars? It's the one that uses a single swivelling wheel in the front, and when resistance is encountered (due to the ...