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

learn more… | top users | synonyms

2
votes
2answers
51 views

Are these capacitors parallel or in series?

I am a bit confused. The authors say these conductors are parallel when the switch is on. But to me it looks like they are in series since the handle is insulating. How can you explain that they are ...
-3
votes
0answers
20 views

PARALLEL COMBINATION OF SUPERCONDUCTORS AND RESISTORS [duplicate]

........................please reply to the question above in the picture. I have tried a lot and have thought about it for a long time. Please help me and answer in simple words. AND I REQUEST NOT ...
-1
votes
0answers
26 views

SUPERCONDUCTORS AND RESISTORS [on hold]

In this circuit 9A current is flowing. The current leaves the battery and reaches junction A (meeting point of resistor of 3 ohm and a superconductor ). So my question is whether all current will ...
1
vote
4answers
707 views

Why are exothermic reactions easier than endothermic?

If we talk about electric heating then we have simple elements in which we apply electrical energy which gets converted into the kinetic energy of the electrons which heats it up. But while cooling, ...
1
vote
0answers
33 views

Determine potential function given initial conditions?

Assuming a radially symmetric circular disk (let's say r=1). Given two simple initial conditions: Potential at the centre is 4 V Potential at the edges is 0 V How would I determine the potential ...
1
vote
4answers
159 views

Why is the total potential difference in a circuit the sum of the individual potential differences?

I am having difficulty in applying my understanding of electrical potential to circuits. Why is the total potential difference in a circuit the sum of the individual potential differences among ...
-1
votes
0answers
45 views

Electric Circuit Simplification [closed]

I have been given a problem to simplify this electric circuit diagram: However, as it's quite unusual for me to see resistors connected in such way I couldn't complete the problem even after ...
3
votes
1answer
119 views

What does a voltmeter actually measure?

For time varying fields (even quasistatic ones) the electric field is given by $${\bf E} = - \nabla \Phi - \frac{\partial {\bf A}}{\partial t}$$ So what does a voltmeter measure? Does it measure a ...
0
votes
3answers
25 views

Finding equivalent capacitance between A and B, [on hold]

Following is the question, asked is to find equivalent capacitance between A and B. I've tried couple of times and getting 7/3 micro farad as the answer while the correct answer is 8/3 micro farads. ...
1
vote
1answer
44 views

Bulbs in parallel/series (very basic) [on hold]

I need some help understanding very basic circuit concepts, specifically for the question in the image below. So from what I know is that in a series setup: voltage is divided over the components, ...
0
votes
0answers
29 views

Calculate the total impedance of this circuit [on hold]

I'm not very familiar with impedance calculations using complex numbers and I would like to ask for a verification for my reasoning in the the following problem. The problem is to calculate the total ...
4
votes
4answers
53 views

Current in inductor just after switch is closed

I have read that the current in an inductor resistor circuit just after closing the switch is zero. This is derived by finding the differential equation in terms of current by using KVL. Is this true ...
5
votes
1answer
234 views

Are magnetic hysteresis losses relevant to alternating currents flowing in a wire?

Say we have an AC in a magnetically lossy material, like iron. Because of iron's relatively high permeability, skin effect will be more pronounced than it is in say, copper, so this iron wire isn't so ...
0
votes
0answers
10 views

Charges on outer faces of parallel plate capcitor

Can there be charges on outer charges of a parallel plate capacitor if both the plates are initially charged by different amount and then connected with a battery.
1
vote
0answers
27 views

Question about notation in a simple circuit [closed]

I was given this circuit in an Electricity & Magnetism course. On the far left, is that a current source providing 2A? It seems to be but I'm not 100% sure.
0
votes
1answer
18 views

Difference between energy loss at high voltage and high current

When reading about power transmission one very common statement is that power is transmitted at high voltage to minimize loss in the form of heat. What confuses me is the governing equation. Aren't ...
0
votes
1answer
124 views

Back EMF & Current, how can we make the current $I$ stable?

Lets assume we have a wire that has $10V$ across and $1$ $Amp$ flowing, now if this conductor is introduced to a changing magnetic field, $-EMF$ is induced, can we control our voltage to increase it ...
0
votes
1answer
126 views

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.
-1
votes
0answers
15 views

Diode Circuit analysis [migrated]

how can i solve circuits like this ?! how current flow though determine the diode modes and calculate V and current in branches
1
vote
1answer
24 views

Is a real voltaic cell always schematically equivalent to an ideal battery and a resistor?

In the diagram I have attached, the top circuit is the schematic equivalent I am trying to use to model the middle circuit which uses real voltaic cells (that have internal resistance). I am not sure ...
0
votes
1answer
17 views

Speakers made from two plastic cups, a copper coil, two magnets and some wire: Advice on how to make it louder? [closed]

http://i.stack.imgur.com/ioQTj.jpg http://i.stack.imgur.com/P09CD.jpg Pics above, in side there are two magnets. I have an assignment in my AP Physics 2 class, I need to make speakers that can be ...
-4
votes
1answer
29 views

E. M. F and potential difference [closed]

Here i =emf/R+r -(eqn.1) . Pd across the cell is equal to potential drop across resistence R. i. e pd =iR . Pd = (emf x R)/R+r -(using eqn. 1) . Also pd =emf -ir . emf -ir =(emf x R)/R+r . Hence ...
-3
votes
1answer
20 views

Mechanism by which a capacitor is charged, using surface charges

I want to gain a deeper understanding as to how a capacitor actually gets charged. Consider a situation in which an uncharged parallel plate capacitor is connected to a battery using two wires. I ...
0
votes
0answers
17 views

Alternating current in a L-R circuit [closed]

I am having some problem in a numerical. But my answer didn't match. The question is here- An electric bulb is designed to consume 55 W when operated at 110 volts. It is connected to a 220 V, 50 Hz ...
-1
votes
0answers
20 views

Current in a series L-C circuit [closed]

Suppose an inductor-coil, a capacitor and an AC source of rms voltage V are connected in series. Now if the frequency of the source is varied, what is the condition for the maximum rms current in the ...
0
votes
1answer
237 views

Calculation of RMS current in half wave rectifier

While calculating RMS current in half wave rectifier, why we will consider only half wave that means only we consider the limits 0 to pi. But here RMS current is for AC input..so why don't we consider ...
1
vote
2answers
685 views

How is the current flow perpendicular to the wire?

This answer gives a great explanation of how surface charge builds up to force the current to move perpendicular to the wire: http://physics.stackexchange.com/a/102936/41086 However, it fails to ...
0
votes
0answers
16 views

BJT transistor as an amplifier [migrated]

I'm confused about a couple of things concerning the transistor.. is Vcc the signal to be amplified or Vin? And does the transistor actually amplify the voltage fed to it or does it just regulate how ...
2
votes
2answers
143 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 ...
1
vote
2answers
328 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
1answer
58 views

Can we “use” a capacitor while simultaneously charging it?

I know that capacitors can be charged to work like a battery . But I wanted to know whether we can charge a capacitor while it is in use ( given that the current supplied to it is more than what it ...
-1
votes
2answers
51 views

What is the reasoning behind calculating the resistance between two points on a square resistor circuit? [closed]

Here, the question asks me to work out the resistance between X and Y. The answer is 1.2 ohms. In a normal circuit, the resistance between two points is simply whatever resistor value(s) is between ...
0
votes
2answers
19 views

Help with electrical current and resistances [closed]

I am working on a physics equation on electrical circuits. I understand it in one direction but I am having issues looking at it backwards. I am given the following: R1 = R2 = R3 = 1.5 Ω Calculate ...
-1
votes
2answers
65 views

Electrocuted at Parking Pay Station After Snorkeling [closed]

This is my first time posting here so bear with me. Also, the circumstances are strange so I am posting quite a bit of detail because I don't know what is relevant and what is not. The short story is ...
4
votes
5answers
148 views

Why aren't resistors equivalent to breaks when $R\to\infty$?

Find the voltage across each resistor as $R\to\infty$ Kirchoff's voltage law gives $$10\ \mathrm{V} - V_R-V_R = 0 \implies V_R = 5\ \mathrm{V}$$ However, don't we get two holes in the ...
0
votes
1answer
23 views

making sense of measures in electronics

I am in secondary school in the UK, and at this point in physics the information we are given is very vague at a fundamental level. My main concern is with electricity and circuits, and the measures ...
0
votes
2answers
227 views

Current on both sides of a capacitor

When a capacitor is connected to a DC circuit, what ensures that the current on both sides of the capacitor is the same? When charges arrive at one end of the capacitor they stop moving; presumably ...
-1
votes
2answers
24 views

AC circuit having a capacitor

Consider a parallel plate capacitor connected to an AC. The current in the circuit leads the emf by $\pi /2$. My question is, what does it mean that the current lead the emf by $\pi/2$? Does it ...
0
votes
1answer
20 views

Internal resistance of a cell

I'm a pre-university student, during the lesson of internal resistance r, there's actually resistance in battery or a cell, and if we were to connect it up in a simple set up as below: The situation ...
4
votes
2answers
244 views

What is the area in Faraday's law if we have only a piece of metal moving in a magnetic field?

If a piece of metal of length $l$ is moving with a speed $v$ in a region where there is a uniform magnetic field $B$ perpendicular to it, there will be a potential difference across its terminals ...
1
vote
1answer
32 views

Ohm's law deviation

In terms of superconductivities and diodes (I do not know anything else except these), Ohm's law deviate from a linear relation. I search many titles or tags for this but I did not understand properly ...
0
votes
2answers
260 views

Close or open circuit?

A electric source provides a non electrostatic influence on the charges inside the source which pushes the positive charges from the negative terminal to the positive one. Does this happen when the ...
-1
votes
0answers
32 views

Why both fuse and earthing ???' [migrated]

This question arose in my mind today that when you already have the fuse for safety precautions why do you need the earthing?
-2
votes
1answer
46 views

How do I simplify this complex resistor circuit? [closed]

I have this circuit diagram and I need to find the current through the circuit.But I have no idea how to simplify this circuit. I have tried applying Kirchoff's Current Law but could not do it. ...
0
votes
1answer
36 views

Resistance from $I$-$V$ graph

I thought that the answer was obviously A as the gradient remains constant...however, the answer is B...who so?
0
votes
3answers
35 views

EMF or terminal voltage?

I have a doubt that is: What does this statement mean: "a 6 V battery". Does this mean that the EMF of the battery is 6 V or the terminal voltage of the battery is 6 V? If the battery has internal ...
0
votes
2answers
42 views

Contradiction about cross-sectional area being inversely proportional to resistance

Let us consider a fixed voltage. $ I = nAve $ is the relation between current, number of free electrons in unit volume $(n)$, cross-sectional area $A$ and electron drift velocity $v$. ($e$ is the ...
0
votes
2answers
51 views

Why don't capacitor charging graphs look like other exponential growth graphs?

Sorry if this question is stupid, but I can't find any answers for this online. Physics websites show that capacitors charge and discharge exponentially. The discharging graphs of charge against time ...
0
votes
2answers
4k views

Calculating the energy supplied by a battery

If you wanted to calculate the energy supplied by a battery in time $t$ you would use $E=VIt$ where $I$ is the current through the battery. If the internal resistance is $r$ we could also use ...