Voltage is the unit of measurement for electronic potential, from one point location to another.

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How to control a dc motor?

I am in 8th standard and I am doing a project on 3d printing pens. I want to know how to control a dc motor, so that when I press a button it should increase its speed gradually till it reaches its ...
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2answers
38 views

Understanding parallel plate capacitors [on hold]

I need help with understanding this assignment. I originally though of using the equation of Eo*A/D = Q/ΔV but I don't know how to answer this without actual numbers to plug in besides the epsilon-not ...
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97 views

Charging by induction [on hold]

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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2answers
310 views

Should the electric potential of a positively charged sphere be negative?

Because the indefinite integral of the electric field results in a negative value? (As the function is proportional to $r^{-2}$? I've got to be missing something... Help please!! Thanks! Also, I ...
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24 views

Determining initial voltage across a capacitor [on hold]

This one has got me stumped. I have a graph of voltage vs time and a corresponding power vs time graph. Taking the integral of the power vs time graph gives me the work done on the capacitor. Now the ...
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19 views

Voltage wave reflections in transmission line loaded by matched resistor

Suppose I have a power source, a transmission line and a resistive load all connected together and all sharing the same impedance. If I send a voltage pulse starting at the power source, traveling ...
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1answer
182 views

Measured voltage on coil

I have a simple circuit of coil with inductance L $$u_c(t)= -L\frac{di}{dt}$$ and AC source with output voltage $u_s$ What is actually measured by the voltmeter ($u_c$, $u_s$ or $u_s - u_c$)? If ...
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1answer
15 views

Build a device that can set voltage according to intensity of the light shined [closed]

I want to build a device that uses photodiodes and photoresistors to set the voltage in the circuit that shines a bulb. The idea is simple. When the light is intense, the bulb should shine less, when ...
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4answers
121 views

Voltage - Energy drop

I'm having a hard time understanding the nature of voltage and am hoping you guys can help. The main issue is the concept of the voltage drop. Take the following circuits : In regard to the first, ...
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1answer
72 views

From your 2 point charges, does the electric field fall off like $\frac{1}{r}$ or $\frac{1}{r^2}$? [closed]

From your 2 point charges, does the electric field fall off like $1/r$ or $1/r^2$ , or somewhere in between. To determine the behavior, calculate the coordinates for several equipotential surfaces and ...
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2answers
291 views

How does back-emf oppose the input-current?

A circuit, has current $A$ flowing at a certain $V$. When there is a change in magnetic-flux, based on Faraday's law of induction & Lenz's law, we know that there is change in Potential ...
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1answer
112 views

Spherical magnet inside a solenoid

When passing a bar magnet through a long solenoid why is it that the induced emf when the magnet is in the middle of the solenoid is zero? And if a spherical magnet is put inside the solenoid, will ...
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2answers
139 views

Does charge of a metal charged by induction determine by which ends of the metal is grounded to?

Does charge of a metal charged by induction determine by which part of the metal is ground to? I draw a diagram to make it simple to understand: Right diagram: When ground is touched with the ...
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4answers
701 views

If induced voltage (back-emf) is equal and opposite to applied voltage, what drives the current?

Suppose we have a circuit with a voltage source, a switch open and an inductor all in series. If we close the switch, the potential difference of the voltage source is instantaneously applied to the ...
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3answers
78 views

What changes in the electrons before and after a voltage drop?

It is easy to visualize gravitational potential energy as a function of the position of height, and a change in this potential is manifested in a change in height. Further, by the work-energy theorem ...
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1answer
243 views

Which power equation to use: $P = I^2 * R$ or $P = V^2 / R$?

Given are ideal max voltage $V = 200\;\mathrm{V}$ and max current $I = 5\;\mathrm{A}$. Therefore: ideal resistance is $$R = \frac VI = \frac{200 \;\mathrm{V}}{5\;\mathrm{A}} = 40 ...
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3answers
909 views

How is a potential difference created between two points?

I would like to know how potential difference is created between two points?Is potential difference created by adding more electrons at one side?If that's the case how to add more electrons at one ...
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3answers
1k views

Measuring voltage drop from induced current

I'm having trouble connecting voltage drops and induced current. Imagine you have a triangular loop make up off three resistors. You place this loop in a constantly changing magnetic field. This ...
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1answer
531 views

If I charge a battery using a much higher current, can it explode?

If I have a 12V 4Ah lead acid battery and use a battery charger that, let's say for example, can charge 10A, 50A, or 100A. If I theoretically turned it to 100A will the battery explode? I understand ...
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0answers
20 views

Potential difference across a resistor

I would like to know if the potential difference between the two ends of the resistance is same as the potential difference between any tow points in the resistance whose length is smaller than the ...
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2answers
43 views

Kirchoff's rules and inductance

Can Kirchoff's loop rule be applied in a scenario involving an inductor? Kirchoff's loop rule states that the closed loop integral of E dot dl is equal to zero. But, in a situation with an inductor, a ...
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1answer
40 views

Electric field along a wire and load

I have referred to many books and all of them apply loss in potential across a resistor only in case of circuits. However, the electric field is present in the whole conductor. Hence the electrons ...
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2answers
1k views

A confusion in ohms law $V = IR$

ohms law clearly states that potential difference is directly proportional to the current flowing through the wire or V directly proportional to I ______(i) so the formula which is ...
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1answer
111 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 ...
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1answer
129 views

Current and Resistance-Effects of the Length of the Wire

Two wires of the same material are both connected to a 9-V ideal battery. They have the same cross section area but wire 2 is twice longer than wire 1. Compare the following quantities by answering ...
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3answers
604 views

Should the term Watt's Law be used for $P = IV$?

I'm revising some electrical curriculum for a technical training program. In the curriculum students have to calculate values using Ohm's law and the equation $$\text{Power = Current * Voltage}$$ ...
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1answer
33 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.
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1answer
36 views

Applying Kirchoff voltage law to a short circuit

If you consider an ideal wire with no resistance that shorts an ideal battery, the only voltage drop that exists is the emf of the battery, with nothing to balance it. Obviously in the real world ...
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11 views

How polarized object's polarized atoms behaves like charge?

Electrical polarization is just the shifting of the constituent atoms' protons and electrons in opposite directions. This creates a bound charge, and this bound charge creates voltage and thus an ...
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2answers
113 views

How does voltage divided by EMF show efficiency?

I get that electromotoric force (emf) is energy per coulomb supplied and that voltage is energy per coulomb used but I don't get what it means when we say that the voltage divided by the emf gives the ...
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8answers
3k views

How do electrons “know” to share their voltage between two resistors?

My physics teacher explained the difference between voltage and current using sandwiches. Each person gets a bag full of sandwiches when they pass through the battery. Current = the number of people ...
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0answers
22 views

Modeling the working of a transformer by pushing magnet into a coil

Let me go step-by-step. First I will outline a simple transformer. There are two circuits next to each other (not touching). One is an electromagnet set-up (with AC supply) and the other has a ...
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27 views

Best Piezoelectric crystal [closed]

Which piezoelectric crystal produces the maximum voltage? Pls help. Thanks in advance
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1answer
36 views

Is the electric field in the wires of the parallel circuit always the same and how that affects current?

When we connect two resistors connected in parallel with a battery, it creates an electric field through this wire. well, my question here: Is the electric field in the main wire is the same as the ...
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1answer
43 views

Voltage and Current

I know that as voltage increases, current increases by $V=IR$, but I really find some difficulty in understanding this at the atomic level (what happens with the electrons inside that wire). I ...
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4answers
6k views

Relation between Power, Voltage and Current when one or more of them is amplified?

$$\text{Power}(P) = \text{Voltage}(V) \cdot \text{Current}(I)$$ If voltage or current is amplified or multiplied what happens to power and current. Does this affect in increase or decrease in power ...
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1answer
32 views

Current through resistors crossing each other [closed]

Calculate the current shown by the ammeter A in the given circuit. I've searched the internet but didn't know how to search for it. Please help
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66 views

Which light bulb will burn out? [closed]

We have 5 light bulbs connected in series assuming all bulbs have identical characteristics. The environment is identical for all bulbs. Wire is superconductor (0 Ohm) and is thick enough to deliver ...
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2answers
680 views

Electric power for current density

The electric power produced by a current $I\in\mathbb{R}^+$ and a voltage $V\in\mathbb{R}^+$ is $$ P = IV. $$ Now the current is given as an (alternating) current density ...
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2answers
42 views

Voltage and Current in an Electromagnet

I'm having a little bit of trouble with electromagnets. I know that a magnetic field is induced by current flowing through a conductor, but what role does voltage play? Does it have an effect on the ...
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37 views

What were the experiments performed that lead to ohm's Law

How was the relationship of $V=IR$ first developed? What were the experiments that were preformed that lead to Ohm's Law? I understand that they had devices during George Ohm's time to measure current ...
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22 views

Fréedericksz transition question

What is the lowest voltage needed for a Fréedericksz transition to occur?
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0answers
22 views

High voltage arc stability reasons (in some cases shape of the arc is rapidly changing)

When turning off 500kV switch we can see an arc like on this picture this arc is very unstable, curved, distorted. It consists of many little loops. While on this picture electric arc patiently goes ...
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2answers
494 views

Does voltage drop occur with zero load and zero resistance [duplicate]

Imagine a circuit consisting of just a battery and conducting wires which have zero dissipativity so that there is no loss of energy( Zero resistance). If the wires are connected to both terminals ...
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1answer
90 views

How to draw + and - and $\nabla \times E$ on a circular wire?

Faraday's Law: $$\vec{\nabla}\times\vec{E}=-\frac{\partial\vec{B}}{\partial t}$$ Circulation of electric field: For time-varying magnetic field and a closed wire, How can we add + and - pole ...
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4answers
90 views

How could a current passing through a resistance create a voltage as predicted by Ohm's Law?

I have a question about the classic relation $V = RI.$ I know that is the voltage that creates the electrostatic force. But I do not understand how, in a circuit with just a current source and a ...
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1answer
30 views

Induced EMF dependent on terminal wire connection?

Figure(a): When a conductor moving inside magnetic field, of a given length at a certain velocity the induced EMF is: $$\epsilon = vBL$$ However, what if we changed the position where the bottom ...
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1answer
40 views

How to calculate resistivity of ring [closed]

Q: In a resistance experiment, a gold ring was connected into a circuit as a resistor. The connections touched on diametrically opposite points on the circular ring. Its diameter is 2cm, and the ...
0
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1answer
52 views

Voltage and Energy in a capacitor [duplicate]

Well, my first question is related to the energy of the capacitor. Why does the energy of capacitor equals $E=\frac{1}{2}QV$ and not $E=QV$;in other words, why we multiplied it by $\frac{1}{2}$?? My ...
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4answers
66 views

Resistor and voltage drop [duplicate]

I know that a voltage drop of a resistor is the energy lost from the potential energy of the electrons.well, what i am really confused about is why the potential energy of the electron decreases as it ...