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

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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
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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 ...
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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 ...
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1answer
37 views

Basic circuit problem [closed]

The voltmeter has infinite resistance. What are the readings on the voltmeter when the switch is open and when it is closed? I thought that the reading on the voltmeter would be E/2 ...
2
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4answers
1k views

Difference between $I^2R$ and $V^2/R$ and $VI$ for measuring power $P$

We use $I^2R$ or $V^2/R$ or $VI$ for measuring power $P$. Are all of these applicable for all circuits? I have seen in some circuit $V^2/R$ is not equal to $I^2R$. Why is that?
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0answers
35 views

RL vs RLC circuit magnetic field

If I want to create an alternating magnetic field using an inductor, what difference would it make to use a series RL or a series RLC circuit ? How will the presence of a capacitor affect the magnetic ...
0
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4answers
36 views

Light bulbs in Series

In physics we were learning about how in series the current is the same through each resistor. So that the lightbulbs will all have the same brightness but dimmer than if there was just one bulb on ...
0
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1answer
28 views

Magnetic field of a solenoid vs magnetic circuit

The magnetic field in the middle of a solenoid is : $$B = \frac{\mu_0 N I}{L}$$ where L is the length of the solenoid The magnetic field in the air gap of a magnetic circuit with constant cross ...
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0answers
21 views

Doubts wrt Electromotive force

The definition of emf states that when a cell is in open circuit , the potential difference between the terminals of the cell is called the emf. Now i dont understand that how can p.d. be taken into ...
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0answers
4 views

Working point of a transistor circuit [migrated]

I've stumbled upon this problem which involves a circuit with 2 transistors that are connected to each other. I'm trying to find a) the "working point" ($V_{ce}$, $V_{be}$, $I_c$, $I_b$) of each ...
4
votes
2answers
188 views

Will the two capacitors be charged in this circuit?

Is such a circuit possible to exist with the two capacitors charging? Because if we considered the outer loop using Kirchhoff's law we get: ℰ = q1/C1 + q2/C2 But since the two capacitors are ...
-1
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0answers
22 views

Two charged conducting spheres when placed in contact with each other [duplicate]

What happens when two charged conducting spheres of different radii are brought in contact with each other. How does it affect the charge distribution and field lines of spheres?
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1answer
30 views

Why is the electric field homogenous inside a circuit?

In a circuit between to poles of a battery, there is an electric field accelerating the charges in the wire towards lower potencial (but due to resistivity they only travel at drift velocity). Is ...
0
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1answer
18 views

How is a change in capacitance detected in a touch-screen?

So the screen has lines of conductors horizontally and vertically, seperated by a dielectric, and thus forming a grid of capacitators where the ones in one "row" are in parallell on the one side, and ...
3
votes
1answer
106 views

Do light dimmers save energy and lower your electric bill? [closed]

Or do they just capture the incoming energy and turn it into heat at the unit and save you nothing?
14
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8answers
2k views

Why is capacitance defined as charge divided by voltage?

I understand that capacitance is the ability of a body to store an electrical charge and the formula is $C=\frac{Q}{V}$. What I don't understand, however, is why it is defined as coulomb per volt. Of ...
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2answers
38 views

Steady state RLC circuit analysis

In an RLC series circuit let applied EMF be given $V=V_0\sin\omega t$, $$Z=Z_C+Z_R+Z_L=R+i\left(\frac{1}{\omega C}-\omega L\right)$$ $$|Z|=\sqrt{R^2+\left(\frac{1}{\omega C}-\omega L\right)^2}$$ Then ...
0
votes
1answer
107 views

Why does a battery die more quickly when more resistors are added to the circuit?

I will be explaining what I think: A battery acts like a pump which provides energy to do work on negative charges to move them towards the negative terminal, and hence creating an electric field. ...
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vote
3answers
674 views

Theoretical uncertainty of a circuit's total resistance when made entirely of resistors

My question in short(ish) is: Will the fractional uncertainty of a circuit made entirely of resistors with equal fractional uncertainties be the same as the fractional uncertainty of those resistors. ...
0
votes
1answer
403 views

Voltage across an inductor contradicts Lenz's law?

Imagine a simple circuit consisting of an alternating current source connected to an inductor. Assume they are connected in the following fashion: AC source - terminal A - Inductor - terminal B - AC ...
0
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1answer
42 views

Question for power and Ohm's law [closed]

I have two questions specifically. Can the usage of Ohm's law be utilized to predict current, voltage in circuits such as parallel, complex and series? How would I explain this? How does the power ...
1
vote
2answers
482 views

Why the EMF of a battery doesn't depend on distance between the two electrodes?

I have read that resistance of a conductor is directly proportional to its length. So, the EMF of a conductor (electrolyte of battery) should increase with increase in length/distance between the ...
0
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1answer
28 views

Capacitor and inductive coil in AC circuit

Does increase in $L$ of inductive coil with variable no. of turns or $C$ of capacitor with changeable capacitance increase frequency of the circuit?
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0answers
22 views

Power formulas? [duplicate]

Are different power formulas in circuits used for different reasons? For Example Power = V^2/R Power = I^2/R Power = VI
0
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1answer
26 views

If a battery is open on one end but connected on the other, does it raise the potential on the connected end?

If a battery has one end open and other end connected to a circuit will the battery increase the potential at the point of connection?
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1answer
31 views

What is the work done by battery and what does work done on battery mean?

Suppose we have a charged capacitor connected to a battery. Now we push the plates of the capacitor away from each other decreasing capacitance and hence energy stored in the capacitor decreases. Now ...
0
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1answer
143 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
0
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5answers
95 views

Brightness of 2 Lightbulbs hooked up to Capacitor [closed]

The figure shows a circuit consisting of a battery, a switch, two identical lightbulbs, and a capacitor that is initially uncharged. a. Immediately after the switch is closed, are either or both ...
3
votes
2answers
71 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 ...
0
votes
1answer
605 views

Is this a series or parallel connection? [closed]

I am confused how the capacitors in this circuit are connected. $C_4$, $C_6$ and $C_5$, $C_3$ appear to be parallel, but both $C_4$ and $C_6$ seem to be in series with $C_1$ as do $C_5$ and $C_3$. Am ...
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2answers
37 views

Why do people say that 'power flows' into or out of a component in an electric circuit?

Currently, I am learning about electric circuits, and how to apply the basic concepts of physics, like work and energy. But I keep running into the same phrase--on Wikipedia, my textbooks, ...
0
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0answers
11 views

Graph of Thermistor against Temperature [migrated]

Assume that I had a circuit as such above. I was wondering, if I increased the temperature of the surroundings, what would a graph of the temperature/PD graph look like? I know that Resistance ...
0
votes
2answers
49 views

Why is a circuit of linear elements itself linear?

A resistor's voltage is proportional to it's current. V=iR. And a source maintains a constant voltage or current. So these are linear, time independent relations. If I put combinations of them in a ...
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2answers
30 views

Phase difference in currents in parallel RC circuit

shouldn't the phase difference be 0. The potential difference across any branch at any instant should be V.so what's wrong ?btw correct answer is (C)
1
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1answer
115 views

Flux linkage of 2 coils in series

I have a question from magnetic circuits. I am an engineering student, therefore I will neglect some minor errors. There is a simple magnetic circuit with 2 coils ($C_1$ & $C_2$), with $N_1$ ...
-1
votes
1answer
21 views

On a AC to DC adapter there are +12v wire with 24A and -12v have 0.5A. How many amp this adapter will provide in total? [closed]

I have a PSU of a pc which is 500w. I want to charge a 12v 100ah battery which need 20 amp of current. Is this psu can provide current that I have wanted? Main question is On a AC to DC adapter ...
0
votes
1answer
33 views

Spherical 'capacitor' with only one charged plate

A question I came across asks about two concentric spherical conductors where only the inner sheet is charged. The question first asks to find the capacitance of such an arrangement. The first part ...
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0answers
20 views

Solving traveling wave using the shooting method

The spatially-dependent Hodgkin-Huxley equation for a cylindrical dendrite or unmyelinated axon: where $\frac{a}{2\rho}\frac{\partial^2V}{\partial x^2}$ is a diffusion term $a$ is the fiber radius, ...
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votes
3answers
89 views

Why is $\text{R}$ resistance in $\text{V=IR}$? [closed]

Today I studied about Ohm's law which states- The current through a conductor between two points is directly proportional to the voltage across the two points.By introducing constant of ...
0
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2answers
444 views

Capacitors in a series circuit with dielectric

When a dielectric slab is inserted between the plates of one of the two identical capacitors in Fig. 25-23, do the following properties of that capacitor increase, decrease, or remain the same: (a) ...
0
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5answers
641 views

Why is there a potential difference?

The question then asks for the potential difference between $X$ and $Y$, which is claimed to be $3.6\text{ volts}%$. Why would there be a potential difference in this case? If I connect a lightbulb ...
1
vote
1answer
31 views

Charging of a battery

A battery has an Emf 6 Volts. It is completely discharged. It is charged by maintaining a potential difference of 9 Volts across it. If the internal resistance of the discharged battery is 10 ohms, ...
0
votes
1answer
19 views

Does the thermal expansion of a conductor contribute to its change in resistance when it is heated?

We know that the resistance of a conductor varies with a change in temperature and we are taught that this change occurs due to the change in resistivity of the material but does the thermal expansion ...
0
votes
2answers
42 views

Use of rheostat in a potentiometer practical?

in potentiometer practical why a rheostat is used in series to potentiometer wire? as we move the jokey the primary circuit current will also change. so is it to flow same amount of current by change ...
1
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2answers
33 views

What is the player's role in the functioning of a theremin?

I recently see a video on how the theremin works, and wasn't satisfied with the answer. I watched around, but they all seem to give the same explanation. A diagram as below is given, and it is ...
0
votes
5answers
59 views

Why current in series circuit is the same?

I have read in the internet that the charges do not have any other path to go and they must go through the same in a series circuit,hence the current is same. It was quite convincing but what ...
0
votes
1answer
25 views

Capacitor in AC circuit

Can someone explain to me the process of discharging of a capacitor when the EMF of AC source is decreasing? And where do charges go? I mean if there's a weak battery, it will be charged but what ...
0
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2answers
34 views

If the potential drops across a resistor (=$V_d$) then shouldn't the potential difference be the $\epsilon-V_d$?

Consider the following circuit: Suppose a current $I$ travels in both the branches, then as the current $I$ passes through the $60$ ohm resistor, there will be a drop in the potential of $60I$. ...
1
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2answers
492 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 ...