The study of the presence and flow of electric charge. Charges, currents, fields, potentials.

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How to insulate static electricity

This is a follow up question to Extending the reach of a crocodile clip for Kelvin Water Dropper experiment. We have resolved the issue, but now we have the following cable (in the image) that ...
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2answers
72 views

Are there alternatives to steam in thermal power stations?

'A thermal power station is a power plant in which heat energy is converted to electric power. In most of the world the prime mover is steam driven. Water is heated, turns into steam and spins a steam ...
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51 views

What effect does voltage have on electron energy levels? [closed]

Is there any effect at all on an electron's energy level when subjected to a voltage?
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1answer
169 views

Induced potential difference paradox

So,i was studying from some lecture notes from MIT's open course program,and i stumbled across this example The example says:The solenoid is so long that its external magnetic field is negligible. ...
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47 views

How paper strips get electrified?

Why paper strips get electrified when we iron them? I have learned that when two insulators are rubbed then they gets electrified but in case of ironing a paper the iron is a conductor. Will rubbing a ...
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94 views

Why does a higher wattage incandescent light bulb have a lower resistance value than a lower wattage incandescent light bulb

I am an electrician and know through experience that resistance in an electrical circuit causes heat. An incandescent light bulb's light is a by-product of heat, so why does a 100w bulb have a lower ...
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0answers
30 views

Why is lightning going from the Earth to the clouds while the electrons are going from the clouds to the Earth?

The lightning is often a discharge in advance. The (negative) charge slide occasionally a little further on in the conductive channel, wherein said channel is highlighted each time something. The ...
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48 views

When heat loss is more than energy generated [closed]

Suppose a electric power station produces 200W of electricity @ 200V. Now instead of stepping it up, it decides to transmit it as 200V to a city 20 km away. The transmission cable has resistance per ...
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83 views

What makes Jacob's ladder spark to go upwards?

In a Jacob's ladder (https://www.youtube.com/watch?v=GaC4BnbH1NY&index=3&list=PL_SAbPKia2YMFi-t8z5WFYCd86Plcs1Un) a spark is originated in the bottom and climbs up to the top. I have read in ...
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24 views

Measuring Static Electricity

Is it possible to measure the static electricity in a room using a VOM or some other digital meter? I have a lot of static electricity building up in a carpeted room, and would rather not spend the ...
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42 views

what would happen to flowing electrons in a vacuum if they are not giving any exit point?

Lets say theoretically electron flow is captured in a vacuum and not allowed to exit then where would they go? I do not want to know the practical impossibilities of it. And also what would happen if ...
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64 views

Touching one end of a battery

What happens when I touch one end of a battery? Is there any flow of charge from the battery to my body? I know that connecting a battery to both ends of capacitor causes the charge from one plate ...
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What are all the lines on a double circuit tower?

I understand what three-phase power is. But when I look at some pictures of a double-circuit-three-phase-power-line I see two or three lines close together? What is the purpose of these lines close ...
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45 views

Explanation of duration of forces due to electrostatic charge

when we use the pen and make the rubbing in it the pen can attractive the paper and after 1 sec. the paper fall down because it loss the earned energy but in this video the balloon still attractive ...
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1answer
55 views

What is the dielectric constant of a pure conductor?

Dielectric constant is the ratio of permittivity of a medium to the permittivity of free space. How to find dielectric constant of a conductor?
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1answer
99 views

How is a variable potential divider able to reduce current/voltage through a component to zero, unlike a variable resistor?

For example, the diagram in my text book shows a filament lamp, in series with a uniform resistive wire, which can have its voltage and current varied by moving the sliding contact, e.g., a ...
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1answer
80 views

Why does compton scattering provide evidence for the particle nature of light?

I understand that compton scattering is modeled as a collision between a photon and an electron, but why does this conclusively prove that light can act as a particle? Why couldn't the same ...
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3answers
55 views

Radiation due to current

Generally we equate change in potential energy to change in kinetic energy but in case of a charged particle like electron this is inconsistent. Consider a case: An electron(of charge e)from rest is ...
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1answer
43 views

Why does a variable potential divider have the ability to reduce current through a component to zero

For example, the diagram in my text book: shows a filament lamp, in series with a uniform resistive wire, which can have its voltage and current varied by moving the sliding contact, e.g., a ...
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2answers
2k views

Getting Deep into Drift Velocity

We know for a metallic conductor Current $\frac{I}{enA} = v$ where $v$ is drift velocity , $e$ is the charge of an electron, $n$ is no of electrons per unit volume and $A$ is area of cross section. ...
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23 views

Separating Interaction of Heat from Electricity?

I have a rod where electricity of frequencies 1-360 Hz is passed through. It is affected by heat. I am evaluating the energy involved in such a process, contributed by electricity and heat. The ...
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14 views

Effect of Electric charge on balloon [closed]

I recently provided a charge to a (inflated) balloon which popped within seconds of introducing the charge ? Why so?
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22 views

Can a moving magnetic field create eddy currents in a conductor ?

Moving a magnet in and out of a solenoid makes a current flow in the solenoid. I know that a changing magnetic field induces emf in a conductor but what about a moving magnetic field ? Are eddy ...
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1answer
28 views

Is the $I^2R$ when a resistive heating element is cool the same as when it's hot?

My system (electric resistance element and water bath) heats up 2 degrees in 20 seconds (0.1 deg/sec) when the resistance element if fully heated. Say I want to raise the temperature 0.1 deg every ...
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3answers
67 views

Inductance coil with self-inductance and resistance

If a coil has $L$ henry self-inductance, resistance of $R$ ohms and potential deferens of $V$ volts what will be the current through it? In my opinion this case should be considered as resistance and ...
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2answers
40 views

Extending the reach of a crocodile clip for Kelvin Water Dropper experiment

We're doing a physics project that involves a version of the Kelvin Water dropper experiment. Everything is working great, and we have the following system: In the image: two plastic containers ...
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1answer
232 views

What is the amount of charge density in a metal wire for the electron's which are involved in current flow?

According to the question Why is charge = nALe n is the charge density (number of electrons per unit volume). Which of the electrons in a metal wire are involved in current flow? Only the unbounded to ...
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3answers
62 views

Photocurrent's dependence on frequency [duplicate]

Sounds like a rookie question, this, but could someone please explain to me why doesn't photocurrent increase when we increase the frequency of the incident radiation? I mean, an increase in frequency ...
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2answers
90 views

Why didn't 0.2A at 2V kill me? [closed]

I was recently connecting a circuit together like here: and I had the voltage set at 2V, with a 10Ω resistor. By Ohm's law, there was a current of 0.2A (and was confirmed by my multimeter). I ...
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2answers
131 views

Charging by induction [closed]

When we charge an conductor by induction and grounding, we first bring a negative charge to the conductor. As a result the mobile electrons of the conductor get repelled and stay far from the negative ...
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4answers
6k views

Capacitor Charging and Discharging when connected to the ground

When we charge a capacitor using a battery and then remove the battery, the plates of capacitor becomes charged. One holds positive charge and the other one gets equal negative charge. o. k. ? Now ...
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2answers
62 views

How to find the current source Is and the voltage V1 of this circuit schematic? [closed]

I have Vs= 1.5V, R1=1 Ohm, R2 =6 Ohms, I got the equivalent resistance to be 7 Ohms. Then I set equal Req to Vs for 7I=1.5 and got my current source to be 0.214A. Since it is only Vs and Req in the ...
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1answer
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electric potential and other potentials

We know that without potential difference no electric current can flow.If two conductors carrying positive and negative charge respectively then the first one will have positive and the rest one will ...
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Calculating engine starter’s energy use

During a discussion on start-and-stop vehicle technology some bloke began pushing the point that re-starting the car uses stored energy from the battery, which needs to be replenished by increased ...
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34 views

Zero or non zero electrical potential energy of the system

Say you have this scenario: and you wanted to find the electric potential energy of the +q charge Now if you were to find the potential energy of +Q and +q system and add that to the potential ...
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15 views

Discharged AA cell

Why does a discharged AA cell fall over when dropped vertically? A new AA cell will not fall over when dropped vertically from distance of 2.0 cm. A discharged AA cell falls over when dropped ...
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1answer
37 views

AC electricity. I dont know what happens when thevenergy flows both ways in AC electricity [closed]

I know that electricity in AC flows both ways but I do not know what happens when it flows both ways. Whats the difference
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4answers
6k views

Why does resistance increase with length?

This is for the case of wires only (pipes are easy). I see that if I place a 9-Volt (constant) battery across any wire, the current is proportional to resistance. I don't understand why, for a ...
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1answer
249 views

What happens to gas molecules after ionization?

I know that gas molecules conduct electricity after they get ionized but what will happen if we keep increasing the voltage even after ionization? Will it explode? If it will then how much energy ...
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27k views

Why is stainless steel a poor conductor of electricity?

I recently had a metal plate put in my shoulder and was wondering why stainless steel isn't a good conductor (At least I hope it isn't). Does the alloy just lack free electrons? Why is that?
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Some Clarifications about Electricity

In the diagram below (ignoring the text), does the $V$ mean that there is some electric field outside of this system which results in a potential difference of $V$ between $a$ and $b$ or does it mean ...
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81 views

Why do bulbs dim when we switch on TV?

Why do the bulbs dim for a moment when we switch on equipments like CRT television or water pump?
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16 views

electrostatics and current electricity

What is the relationship between a closed and open circuits with electromotive force.electromotive force is the force that keeps charge moving in circuit when a potential difference is created.
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20k views

Why don't electric fish shock themselves?

Fish like electric eels and torpedoes have specially designed nerve cells that allow them to discharge hundreds of volts of electricity. Now, while pure water is usually nonconductive, the dissolved ...
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3answers
57 views

Is it possible to avoid static electricity? [closed]

Sometimes I touch a car or a door and I feel the static electricity in my hand and it hurts sometimes. I try not to touch anything because I feel like I am going to feel this pain again. Is there a ...
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1answer
35 views

Charging with No Current

This may be a basic question, but I am not sure about the exact reason, so I'm asking this I've noticed quite a few times that when you plug an iPad charger to a socket and then switch it on, then ...
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1answer
72 views

why do light bulbs explode when in contact with water?

Is it true that when water pours on a light bulb it will explode? If so does this apply to all light bulbs and how does that happen.
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1answer
45 views

Does a capacitor experience a Newtonian reaction when being charged?

Say I have a capacitor that is being charged with a battery. There are two wires, one on the positive and one on negative terminal of the battery which go to a capacitor. During the charging, a ...
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1answer
30 views

Equation relating voltage and minimum rpm needed for generating 1V using a magnet around copper wire

I was wondering if there is any equation or law or something that relates the minimum rpm needed when a magnet spins around a copper wire to generate 1 volt? In other words, how fast does the magnet ...
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Difference between potential difference and electromotive force [duplicate]

What is the difference between potential difference and electromotive force? Potential difference is the work done when 1 Coulomb of charge move one region to another.