# Tagged Questions

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

19k views

### What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)?

This is a confused part ever since I started learning electricity. What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)? All of them have ...
52k views

### What causes an electric shock - Current or Voltage?

Though voltage and current are two interdependent physical quantity, I would like to know what gives more "shock" to a person - Voltage or Current? In simple words, will it cause more "electric - ...
99k views

### Why do we use Root Mean Square (RMS) values when talking about AC voltage

What makes it a good idea to use RMS rather than peak values of current and voltage when we talk about or compute with AC signals.
68k views

### I don't understand what we really mean by voltage drop

This post is my best effort to seek assistance on a topic which is quite vague to me, so that I am struggling to formulate my questions. I hope that someone will be able to figure out what it is I'm ...
78k views

### Why do birds, sitting on electric wires, not get shocked?

If we would touch electric wires, we would get a shock, even if we are not touching ground (so that no connection is complete form wire to ground through us). I always see that birds sit on electric ...
849 views

### Voltage drop along an idealized resistance-free wire in a circuit?

If you connected the positive terminal of a battery to the negative terminal to a battery with a wire with (hypothetically) no resistance, and are asked to give the voltage drop of a segment of wire ...
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 ...
1k 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 ...
1k views

### What determines the forward voltage drop for a diode?

I have always had the idea that the forward voltage drop in a semiconductor diode was related in a simple way to the bandgap energies in the semiconductor. However this is apparently not the case: ...
905 views

### What maintains constant voltage in a battery?

I know there's lots of questions that address similar situations, (Batteries connected in Parallel, Batteries and fields?, Naive Question About Batteries, and the oft-viewed I don't understand ...
432 views

### Justification of root mean square [duplicate]

In the top answer to the question Why do we use Root Mean Square (RMS) values when talking about AC voltage, the following was stated: This RMS is a mathematical quantity (used in many math ...
82 views

### Interpreting Physics Results Regarding Circuitry Analysis (Highschool Level Physics) [closed]

I conducted an experiment which aimed to detail and record the voltage across series resistors in series circuits. I noticed that: The Final Voltage, V3, stayed the same. The resistors with the ...
613 views

### Ohm's Law Intuition

When we derive Ohm's Law using the Drude Model, we assume at one point of time that $E=V/L$, when is fact, $E=dV/dL$, unless $E$ is constant, in which case the assumption $E=V/L$ is true. But I don't ...
4k views

### Could someone intuitively explain to me Ohm's law?

Could someone intuitively explain to me Ohm's law? I understand what voltage is and how it is the electric potential energy and that it is the integral of the electric field strength etc. I also ...
17k views

### Difference between current and voltage sources

I am confused about the current and voltage. My intuitive example would be that of a pipe of say water. The diameter of the pipe determines the amount of water flowing per second but the pressure is ...
735 views

### The Difference Between voltage and current

I know that this question has been asked many times before, and I have read over several of the threads asking this question, but they do not include the gripe I have with my problem of understanding ...
704 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 ...
37k views

### Why does voltage remains same over Parallel Circuit

Why does voltage remains same over parallel circuit. If a resistor is connected in the circuit some of the charge should be transformed into heat and make a lack of charge after the resistor (in my ...
2k views

### What kills you: Voltage or Electric current? [duplicate]

Possible Duplicate: What causes an electric shock - Current or Voltage? When someone gets electrocuted, what kills them; a high Voltage or a high Electric current, and why?
25 views

### High Voltage Powerlines - clarification of energy loss

I've been having a bit of trouble understanding the High-Voltage powerlines. If I was sending power from $A \rightarrow B$, we have: Ohm's law $V = IR$ Power lost in the form of heat $P = I^2 R$ ...
104 views

### $V = V_1 + V_2$ confusion? Why is my “proof ”incorrect? [closed]

Why isn't $V= V_1 + V_2$? $V=V_a - V_c = V_a - V_b + V_b - V_c$, $V_a - V_b= V_1$ and $V_b - V_c = V_2$ Doesn't that prove that $V = V_1 + V_2$? Regardless of $V_3$, If i'm wrong , is there a way ...
12k views

### Why does the area of the plates affect the capacitance?

Why does the area of the plates affect the capacitance? Lets say I have a parallel plate capacitor with a charge of 10C and a potential difference of 5V. By the definition $C=Q/V$, the capacitance is ...
5k views

### How can one derive the Ohm's Law?

I am looking for the derivation of the Ohm's Law i.e., V is directly proportional to I. Can someone help me with it?
8k views

For some reason, I feel like the concept of voltage is escaping my grasp. I've done much research on these forums and through texts, and come across answers that seem quite well thought out, but still ...
448 views

### Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
2k views

### Why doesn't an electron accelerate in a circuit?

Why don't electrons accelerate when a voltage is applied between two points in in a circuit? All the textbooks I've referred conveyed the meaning that when an electron traveled from negative potential ...
422 views

### Voltage drop = more electrons on one side of resistor

I have been asking myself this question for a long time now. Suppose we have two resistors in series connected to a voltage source. Simply put, does the voltage drop on each resistor mean that there ...
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 ...
31k views

### Current without Voltage and Voltage without Current?

At school I've always learned that you can view Current and Voltage like this: The current is the flow of charge per second and the Voltage is how badly the current 'wants' to flow. But I'm having ...
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 ...
603 views

### What is fatal? Current or voltage? [duplicate]

I have been searching this answer for quite a while. I asked my physics teacher and he said it is current that causes death. A friend of mine, who is a EE student, and his answer was voltage. When i ...
5k views

### Does the 'mAh' rating of a battery have something to do with its power?

I'm curious about the 'mAh' of a battery: how can this impact the power of the battery? I've done some research on the internet, and most of the articles I found explain about the 'amount of charge ...
927 views

### Why Two Equal Resistors Cut Voltage in Half?

I've been reading several books on electronics, one of them called "Electronics All-In-One For Dummies - D. Lowe (Wiley, 2012) BBS". It states that if two resistors of the same value, no matter the ...
335 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 ...
1k views

### Hard circuit problem [closed]

I want to find the p.d. between points A and B. I'm not sure how to approach this problem though, could I have a hint?
148 views

### Loopless voltage measurement

I think we are all very well familiarized with the classical voltmeter. Classical voltmeter has two conducting wires that bring two potentials into the box. In the box we have well controlled ...
120 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 ...
155 views

### Calculating the Potential from the E-Field

I find that often times I'll be tripped up by questioning whether or not I can do something mathematically, and be unable to come up with a satisfying answer. This is, unfortunately, one of those ...
268 views

### Why are high voltage lines “high voltage?”

If I have two spheres of the same size and one sphere has a small amount of charge compared to the other that has a lot more charge, then clearly the sphere with the larger charge has a larger voltage ...
156 views

### Help Understanding Non-conservative Fields

While watching a video lecture, I became uncomfortable with the results, (around 35 mins). The professor draws an electric circuit with a 1V batter, and two resistors (1 and 9 ohms). He then ...
139 views

### Capacitors and Voltage

Imagine if I have a capacitor, connected to a battery of $12 V$. After charging the capacitor, I increase the plate separation. Then my capacitance decreases, right? But charge should be ...
30 views

### Plotting the Graph of $1/I$ on the Y axis against R What does this represent? [duplicate]

What does the gradient, the intercepts represent, what is the equation of my line, and how do I use this information to calculate emf?
435 views

### Why can't I connection the anode of a battery to the cathode of an other battery and get a current flowing? [duplicate]

If I touch the anode of a battery or connect the anode the the cathode of an other battery, none (or rather: a very small current) flows between those two. If I instead connect the connect the anode ...
173 views

### Influence of applied voltage to an electron of a metal

I would like to ask what would happen to the potential well of an electron being trapped in a metal? If I apply a voltage trying to accelerate the electron out of the potential well. Would It make the ...
185 views

### Can a liquid insulator be electrically charged by touching a charged conductor?

Can a liquid insulator be electrically charged by touching a charged conductor? I understand that solid insulator will only be charge on the surface where it is touch, but the case is different ...
2k views

### Power dissipated on internal resistance of short-circuited voltage source

Suppose we have a voltage source with an EMF of $\mathcal{E}$ and an internal resistance $R$. If we connect to it a perfect wire with zero resistance, we get a short circuit. The value of the current ...
20k views

### Confusion about P=VI and V=IR

If we look at $P=VI$, we see that if the current doubles then the potential difference is halved but this doesn't seem to make sense according to $V=IR$. If we look at that equation, since the ...
4k views

### Basic questions about voltage drop in DC circuit

I understand all the concepts of what voltage is using all the analogies but some things related to the drop of voltage across a circuit confuses me. If I had a short circuit and attached a ...