# Tagged Questions

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

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### 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 ...
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### 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 ...
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### 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, ...
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### 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 ...
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### 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 ...
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### 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)
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### 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 ...
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### 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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### 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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### 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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### 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 ...
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### 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, ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 $60I$. ...
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### Inductor potential difference direction

If you have increasing current going down an inductor, the inductor will produce a potential difference to produce a counter current in the opposite direction, or up. The lower potential is then on ...
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### 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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### Kirchhoff's laws in phasor domain

While analysing AC circuits, we write voltage, current etc all with complex numbers namely "phasors". While studying the same, I wondered if Kirchhoff's laws held good with current and voltage in ...
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### Is power still consumed when we switch off the lights?

I was having heated discussion with one of my friends. We were discussing Earth Hour and its role in saving electricity, and creating awareness. He stated that even if you turn off the lights, the ...
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### Finding Inductance in an AC RLC Circuit?

In the laboratory you find an inductor of unknown inductance $L$ and unknown internal resistance $R$. Using a dc ohmmeter, an ac voltmeter of high impedance, a 1 microfarad capacitor, and a 1000 Hz ...
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### What happens in the RC circuit when being charged?

Say I have this RC circuit and at the start, the switch is off (current going from left to right and the starting point is just above the battery). I understand that then the capacitor acts just ...
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### With the help of a given charge is it possible to obtain a charge many times greater in magnitude

Consider a spherically conducting sphere. If a charge(say positive) is placed near the sphere, then it will lead to separation of charges inside the sphere.My question is, can we create charges more ...
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### Series circuit of capacitor and ohmic resistance: Voltage drop at Capacitor? [closed]

I have a question to an exercise I am currently trying to solve. It is given an Capacitor and an ohmic resistance in a series circuit. The whole voltage is 40V, the resistor has an resistance of ...
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### Making a conductive paint out of graphite powder [closed]

I want to make a conductive paint out of graphite powder and gum to use as an electrode. What shall be the best gum to use, as i need a low resistance of around some kilo Ohms. I am getting very high ...
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### Which makes for a better equivalent capacitor? In series or in parrallel?

I understand how capacitors in series and in parallel work. However, I am wondering if it makes a difference, in terms of making a better capacitor that can store more charge, would you connect them ...
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### Imaginary component in capacitive reactance

This is a trivial question in first year but, unfortunately, this popped up in an elementary yet compulsory lab experiment. The capacitive reactance is defined as $$X_{c}=\frac{1}{\omega c}$$ The ...
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### Adding two same DC voltage source in parallel

In a parallel circuit(imagine two branches),with one DC voltage in a branch and another DC voltage in a branch, what is the method of computing the total DC voltage? The voltage through each component ...
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### Reducing voltage with resisitors [closed]

I am working on a project in structure, in which i have to rotate the second storey of my building, now my assembly consists of 12 v battery connected in parallel with 12v motor which is connected to ...
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### How does electricity travel through a set of resistors arranged parallel to each other? [duplicate]

For calculating net resistance in a combination of parallel resistors we use 1/R=1/r1+1/r2+1/r3....but electricity must travel through least resistance. Then how does this relation come in use? I am ...
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### Why is it said that electric current always flow from higher potential to lower potential?

Why is it said that electric current always flow from higher potential to lower potential? It is said that current flows from positive terminal to negative terminal, but it is actually the negative ...
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### Logarithm of the voltage of the inductor in RL circuit experiment is nonlinear with time

I performed an experiment about the RL circuit, with following circuit: (I used the PASCO RLC circuit lab.) By Kirchhoff's voltage law, (denoting the emf of the signal generator $\mathscr E$, ...
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### What is the current passing through wire AB as a function of angle theta? [closed]

This is a high school contest(CAP) question: Consider a circuit made of a wire with uniform resistance in a shape of a circle as shown in the picture. The circle is connected diagonally from point A ...
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### Resistance of a plate of smaller plates made up of different materials?

This problem propped in my head yesterday related to a project I'm working on and I just can't figure out how to crack it! If we have a large plate made up of nxn smaller plates, what is the ...
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### How can current remain same when potential difference decreases?

According to Ohm's law, $$\text{potential difference} = \text{resistance}\times\text{current}$$ Also, current remains the same everywhere. Now when current passes through a bulb, the electric ...
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### Is impedance the ratio of voltage to current at any instant?

My book defines impedance as the ratio between the amplitude of voltage to that of the current (Vmax to Imax), I just wanted to make sure whether its also true for the instantaneous values of voltage ...
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### Things that must be considered when mass producing a capacitor [closed]

The question is to list four things that must be considered when a capacitor is chosen for inclusion in a circuit which is to be mass produced. Are there a specific set of four things? I've come up ...
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### To determine the path of current in a complex circuit. (CAP contest question) [closed]

How to determine the path of current in this diagram ? Intuitively, I guess the current won't pass through wire DC... Any help will be appreciated!!!
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### Power dissipation in AC RC circuit [closed]

Can anyone help me with this question? A 20 A peak-to-peak 60 Hz current passes through a 0.01 µF capacitor which is in series with a 33 Ω resistor. What is the power dissipation? I have ...
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### Why electrons flow through a wire connected to a battery?

I would like to know why does electrons flow through a wire connected to a battery as said in AC/DC: What's the Difference?.It tells that "the electrons that are stripped from the carbon electrode is ...
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### Opposing currents in a Ciruit

If I have two currents flowing in opposite directions in a wire where both currents are equal magnitude and their is a bulb on the same wire does the bulb light up at all or is it bright/dim ?
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### 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 ...
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### Why does this circuit work and the other doesn't? [closed]

if we connect the set up like this the bulb glows but if we connect the [right wire] to the [earth of the left] then the bulb [doesn't glow]. Why does that happen?
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### Why does adding more components in parallel increase the current?

Why does adding more components in parallel increase the current? Shouldn't the charges be more distributed, so they can't 'push' each other at the same rate anymore?
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### Movement of charges in presence of electric potential difference

This might appear to be a bad question to some but i can't figure out the answer. While reading about an electric circuit, i found this on the web: Over the course of time, one could think of ...
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### what is the analog of electronics for quarks or protons?

Is there an equivalent field for quarks or for protons as there is electronics for electrons where you can build engineer and mess around with things? May be even hack ?