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

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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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1answer
32 views

Direction of AC current in a very long wire [closed]

Suppose a wire of length 10^8 meter is connected in the slip rings of an AC generator. Taking the speed of current propagation to be ~10^7 m/s, then it takes 10 seconds for current to flow from one ...
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46 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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75 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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28 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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65 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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22 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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2answers
75 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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38 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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61 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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1answer
45 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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43 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
49 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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1answer
63 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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2answers
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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1answer
33 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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3answers
53 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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0answers
22 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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0answers
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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1answer
27 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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2answers
35 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
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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3answers
52 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
84 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
60 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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3answers
65 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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1answer
18 views

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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1answer
32 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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0answers
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
36 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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40 views

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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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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3answers
71 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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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
61 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
43 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
29 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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0answers
29 views

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.
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3answers
52 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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2answers
60 views

Ohm's law experiment

I was going through my physics laboratory manual. In the Ohm's Law Experiment, the book states a few precautions without any reasoning. 1.The wire whose resistance has to be determined should ...
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2answers
65 views

How can “…electrons flow in metals, but not in the ground…” explain grounding rods?

I really enjoyed Why is the charge naming convention wrong? But, in the comments at the very end, the statement that "...electrons flow in metals, but not in the ground..." left me uneasy. I was ...
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2answers
89 views

How does a point charge interact with a Gaussian surface?

A spherical Gaussian surface encloses a point charge $q$. The point charge is moved to to a point away from the center of the sphere. Does the electric field at a point on the surface change? ...
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1answer
59 views

Why is a series resistor needed in a simple thermistor experiment? [closed]

I have come across the following simple question, however I can't see any need for a fixed resistor in series. The only possible reason that I can think of is that the resistance of the thermistor ...
3
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1answer
85 views

Why does energy flow between a high voltage transmission line and linemen approaching it on a helicopter?

The video High power line workers shows linemen servicing a live high voltage transmission line. As the helicopter approaches the line, the lineman reaches out with a metallic wand that is ...
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0answers
19 views

Capacitor charge and current as a function of type question [closed]

Two capacitors, one resistor and an ideal battery are connected through switches s1,s2 and s3 as shown in figure. Initially capacitor of capacitance 4C is charged, while other is uncharged. The upper ...
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1answer
34 views

Resistance of a general resistor [closed]

I have some medium with a resistivity which depends on position. In this material are two electrodes, is there an integral or something which i could numerically integrate to find the resistance ...
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1answer
30 views

If we increase dimensions of a wire, how does electron density change?

If we increase the diameter of a wire, does the electron density change at all? When we increase the diameter or the length of a wire (while solving numericals) do we add appropriate number of ...
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1answer
33 views

I need proof for dW=eIdt [closed]

I need help to understand from where this equation is formed inorder to continue to study energy stored in an inductor.
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1answer
108 views

If increasing applying energy to an atom excites electrons, why does electrical conductivity decrease as temperature increases?

Applying energy to an atom makes the electrons jump up to higher energy levels. This is known as excitation. Electrons on higher energy levels are easier to remove from an atom than those on lower ...
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1answer
66 views

Why doesn't a fluorescent lamp implode even though the pressure difference is very high?

According to Wikipedia, the pressure inside a fluorescent lamp is 0.3% of the atmospheric pressure, so the pressure difference between the outside and the inside of the lamp is almost equal to the ...