# Questions tagged [voltage]

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

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0answers
27 views

### Resistance of Infinite ladder network which have resistances in arithmetic and geometric progression! [closed]

So i know superposition method to solve equivalent resistance problems. But I tried but I don't think it would work here. How we are supposed to approach problem like this. I tried by assuming ...
3answers
44 views

### Why does a voltmeter have to have nearly no current passing through it?

I understand that a high resistance of a voltmeter will allow nearly no current to pass through it. However, why is this condition required? Let's consider a simple circuit that consists of a cell, ...
2answers
48 views

### Why does the current stay same everywhere in a series circuit [duplicate]

Current in a series circuit are the same everywhere, but when there is a bulb creating a potential difference, wouldn't the rate of the same number of electrons flowing, coming out from the bulb ...
1answer
29 views

### Is there a potential difference across the bulb after current passed through a diode?

I understand that voltage can exist without current so what I want to ask is will there be a potential difference across the bulb(situated after the diode) when a batteries supplied energy through a ...
1answer
46 views

### Application of Kirchhoff's rule [closed]

I came across a problem, in which I was supposed to find the power through the 10-ohm resistor, the one at the top (I forgot to label it). I applied Kirchhoff's loop rule and found the current flowing ...
1answer
37 views

### Electricity in the atmosphere: effect on human body and on electric components

there are many topics on the web (for instance this, or this famous lecture) about this topic, but I do not understand some basic concepts. The statement from which I want to start is this (taken ...
4answers
205 views

### Voltage as work in electric field and in Ohm's law

I am struggling to reconcile the definition of voltage as work done moving a unit of electric charge between two points in an electric field and voltage in Ohm's law. In the work definition, ...
11answers
9k views

### Birds on a wire (again) - how is it that birds feel no current? They are just making a parallel circuit, no?

I have been thinking about this and I know that other people have answered this on here, but there's one part that still baffles me, and it has to do with parallel circuits. If I connect a battery ...
1answer
24 views

### Joining two insulators at different potentials with a conductor

If two insulators are connected by a conducting wire, will the charges flow if they are different potentials? According to me, as the charges can't enter the insulators, charges only get distributed ...
3answers
68 views

### Do resistors heat up with left-over amps?

Apologies in advance if I misunderstand and for my bad explanation. I have heard that resistors heat up when there are left over amps that are not being used. If this is the case, why do most home ...
0answers
19 views

### What would the graph look like if the electrodes were non-equidistant from the dipole?

Hypothetically speaking using the diagram above. If the negative electrode was very far away from this excitable tissue and the positive electrode was right next to it. What would the voltage graph ...
2answers
27 views

### Why does breakdown voltage increase with pressure in gas insulators

There are two main theories which I have been reading into Townsends avalanche effect and Paschen's curve. I understand that as electrons move from negative to positive electrode they collide with gas ...
1answer
24 views

### Chloride equilibrium potential is negative shouldn't it be positive?

Chloride flows down its concentration gradient into the cell. At a certain point a minute amount of net positive charge develops on the outside, enough to electrostatically attract chloride ions back ...
1answer
43 views

### Coulomb in Voltage formula is confusing me. What to do?

To make my question clear I've added a picture above which I drew myself which shows 2 scenarios where the only difference is the sign of the charge. Essentially we have an electric field produced by ...
2answers
69 views

### How does a current cause a voltage?

In most textbooks I've read, the explanation of Ohm's Law begins by assuming that there is an external voltage applied to a resistive (Ohmic) device. From there, it is explained that this voltage ...
1answer
25 views

### Is there voltage drops across series resistors with a parallel resistor system?

I am not looking for calculations, I can do that. Please forgive the drawing, my picture wont upload. However, (R1 and R2) are in series. Likewise, (R3 and R4) are also in series. I could not show the ...
3answers
34 views

### Confusion about cells in parallel

I cant understand why cells in parallel will last longer. Could someone please explain?
3answers
49 views

### Current and voltage - Incompatibility between Ohm's Law and Power Law! [duplicate]

Ohm's Law: I $=\frac{V}{R}$: Increasing voltage increases current. Power Law: P $={V}*{I}$: Increasing voltage decreases current. Am I missing something?
0answers
21 views

### How to calculate the battery drain from a LED light knowing it uses 1.5 Ah/month?

My knowledge of physics is basically zero, so I hope this question can be considered on-topic! This thingy connects to the battery of a vehicle (car, motorcycle, scooter etc) and shows the level of ...
3answers
51 views

### Would there be a potential difference across a cell connected with just a wire in complete circuit?

My textbook says, that across a battery or a cell there should be a potential drop equal to its e.m.f. Now consider a simple circuit with a cell of e.m.f 9 V. Let us assume a point on the negative ...
1answer
27 views

### Calculating multipole expansion outside uniformly charged sphere

When calculating the potential outside a uniformly charged sphere with charge density $\rho$ and radius R using the multipole expansion, it makes sense that only the monopole term survives (since it ...
2answers
43 views

### I'm having trouble understanding the formula of Potencial Difference (or Voltage) in Electrostatics

For example, my textbook clearly says that the Potencial Difference between points A and B is given by $$V_{AB} \equiv V_A-V_B = \int_A^B \vec E\cdot d\vec l$$ but I've seen, in other textbooks, ...
1answer
71 views

### How are electric and magnetic fields able to travel through space and wires, and how are they more than mathematical constructs?

Once I was taught that light is physically made up of in-phase E and B fields oscillating perpendicularly, it was a little baffling because I always thought fields were just analysis tools (or even ...
1answer
66 views

### Relation between $V = RI$ and Ohm's law

According to the book Halliday et al., the equation$V = RI$ is not the Ohm's law but simply the resistance definition; the book states this definition applies to all kinds of conductors, ohmic or not. ...
3answers
88 views

### Is there any relation between turn on voltage of LED and the colour emitted?

It is evident from the above V-I graph that longer the wavelength of the light emitted lower is the turn on voltage. I know that turn on voltage is voltage required to have significant current that ...
0answers
5 views

### What is the maximum negative output voltage of an emitter follower with a split +10v/-10v supply? [migrated]

I'm perplexed by a passage in Horowitz and Hill's "Art of Electronics" (1st ed., p. 54). They present the reader with a simple emitter follower circuit. The input voltage is a 10v amplitude sine-...
2answers
44 views

### Why do charges not lose potential as they travel through the circuit before reaching a resistor? [duplicate]

Voltage is defined as: Given the circuit: Why would potential not drop, from the point differentially away from the positive terminal on the battery, to the point I have labeled. I understand that ...
1answer
27 views

### Circuit breaker and capacitance

I have a problem with knowing witch capacitor to use in a circuit because I am working on installing main circuit breaker where it is needed for 220 Volt AC current to be turned in to a lower current ...
1answer
50 views

### Why is high voltage lethal? [duplicate]

Why is it that high voltage is lethally dangerous compared to low voltage with the same amount of current? How does current behave with low voltage and with high voltage? I have read many similar Q &...
0answers
19 views

### Regarding Paschen curves for Venusian air composition

I'm curious what the breakdown voltages look like for the venusian atmosphere, specifically at the surface of venus. How much power and voltage would be required to start an arc, and how much power ...
0answers
20 views

### Microscopic interpretation of constant voltage from Battery

I don't know if this is the right place to ask(Maybe it's more related to chemistry), but this has been troubling me for some while. Consider you have a chemical cell. Then the reason for the ...
0answers
27 views

### How to find the potential difference in a circuit with internal resistance

So I want to find the potential difference between points $a$ and $b$. I'd first need to find the total current in the top and bottom loop (middle one doesn't participate in the circuit). I can do ...
1answer
36 views

### Why is the EMF=terminal voltage in an open circuit

Now a trivial answer would be that the current is 0. V= E-Ir (where v is terminal voltage, e is emf, I is current, and r is internal resistance) Since i=0, V=E But one thing I believe we are ...
1answer
55 views

### How same power is distributed in different voltages in power lines?

I have seen when a resistor is connected to a battery, it carries the same voltage across the resistor, if the resistance is changed the current changes but voltage remains the same making the battery ...
3answers
56 views

### What does an incompleted variable resistor mean physically?

In the diagram below, the resistor has three terminals I believe. Now in this circuit, my book tells me, that only two terminals are being used (to alter the resistance by sliding the metal contact). ...
2answers
89 views

### How is this a parallel circuit?

I understand that here, the current has a choice to flow through one resistor and back to the terminal WITHOUT going through the other. Is this, a parallel circuit? I don't get it. Sorry if this is ...
0answers
23 views

### Why does an oven burn out when all knobs are on? [closed]

I'm having serious trouble understanding this. If a fuse burns out when too much current is flowing through it, then how does turning on all knobs to their full setting burn out the wall-plug? ...
0answers
12 views

### Cylindrical/Spherical Capacitor derivation sign issues

In deriving the capacitance for a cylindrical and spherical capacitors, I keep obtaining the incorrect sign on V. I completely understand the problem besides one step. First we start with Gauss' law:...
3answers
59 views

### Types of circuit

In this image one plate of C1 is at potential of 100v and one plate of C3 is earthened. Which type of circuit is this? If it's open, why would the charge flow?
1answer
37 views

### Electricity, Voltage, Potential Energy

i wanted ask something about electricity: Suppose we have a circuit:a battery and wires connected to two poles. Also suppose wires have no resistance. Well:When electron goes from negative to positve ...
2answers
423 views

### Does an electric current flow in an open circuit?

When the positive and negative terminals of a battery is connected through a wire, an electric current flows across the circuit. Generally, electrons are the ones that flow (from negative terminal to ...
0answers
23 views

### Enquries about capacitance of parallel plates with a dielectric slab between it while being connected to a constant voltage source

As the title suggests, it is a question about parallel capacitors. I believe that it would be hard to understand what my question is if I am going to directly type it out. Please take a look at below. ...
1answer
40 views

### Why is the graph (Voltage vs Current) of an ohmic object not exactly linear?

What are the reasons for the graph Voltage vs Current of an Ohmic object being approximately and not exactly linear? In other words, we accept its lineality, but in reality, it is not exactly linear. ...
1answer
53 views

### Capacitance absurd equation in textbook help [closed]

In a textbook I have this equation: $$I_0 = \frac{q_0}{RC} = \frac{V_0}{R}$$ I tried calculating this, can someone please explain this? $R$ is resistance, $C$ is capacitance, and $I_0$ and $q_0$ ...
9answers
2k views

### How does the current remain the same in a circuit? [duplicate]

I understand when we say current, we mean charge (protons/electrons) passing past a point per second. And the charges have energy due to the e.m.f. of the power supply. Now tell me, if a lamp has ...
1answer
52 views

### What is the electric potential in free space? [closed]

What is the electric potential in free space? Is it not zero, since there is no charge around?
1answer
26 views

### Transmission voltage [closed]

I don't understand how to calculate transmission voltages I thought you needed the length of the lines to do it but I haven't been given one. https://imgur.com/a/kLOzLCQ
3answers
88 views

### $V$-$I$ characteristic of a solar cell

please explain the VI characteristics of a solar cell. The characteristics is given in my book without any explanation. How can the Voltage decrease on increasing current shouldn't it be opposite. ...
1answer
59 views

### Confusion about the impact of resistance in a parallel circuit

If two bulbs are connected in parallel circuit with a variable resistor attached to the one of the branches and the resistance is decreased, what will be the effect on the brightness of the both bulbs?...
4answers
115 views

### Clean link between electromotive force and difference of potential: potential difference around a resistor or inductance

I would like to clarify some aspects of EM that I never realized before: proper link between voltage in electric circuit and electromotive force. Electrical vision of electric circuit: In almost all ...