# Tagged Questions

20 views

### heat energy and resistance of an elctric circuit

Very often it is said that "heat is developed" in a resistance when there is an electric current in it. But as far as I know heat is defined as a form of energy being transferred due to difference in ...
69 views

### How does current flow in a irregularly shaped heterogeneous resistor?

The motivation for my question is understanding how electricity gets through your skin as opposed to running along it, and how the presence of things like water on the skin affect the relative ...
30 views

### Would the empirical behavior of a simple circuit match my model of it?

I have a practical problem in E&M which has baffled me and and my electrician. The copper water pipes in my house are carrying a current of small potential (~1V) AC current. Here is my ...
138 views

### Does rubber insulate lightning more effectively than air?

Last week, an Ars Technica writer was struck by lightning. He says that the 911 operators were concerned about whether or not he was wearing shoes at the time, but he didn't think it would make much ...
42 views

### Resistance of a copper wire [closed]

Resistance of a copper wire is 20ohm. If the diameter of the wire is 5mm and length 1ohm. Find the resistivity of the copper.
66 views

### Is this series or parallel? [closed]

How do you find I? and please explain which resistors are in parallel and which are in series? ("M" and ">" are resistors) ...
170 views

### How exactly does a resistance reduce current?

I've heard that resistors are used to decrease current to a particular appliance, such as in the regulator of a fan. However, I've also heard that the total current in a circuit is always the same- in ...
904 views

### Physical interpretation of y-intercept in a Current vs Voltage graph

So I collected current and voltage data from a simple circuit with a power source and a resistor, using a multimeter. I created a graph for this data using excel and got the y-intercept (which is ...
785 views

### Ohmic and Non-Ohmic devices

Why do some conductors follow Ohm's law and some do not? Isn't there any universal law that can explain the flow of current?
368 views

### How to find the equivalent resistance for the following circuit? [closed]

How do you find the equivalent resistance for the above circuit, if current is entering via A and leaving via C? Can it be done by treating it like a wheatstone bridge?
807 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 ...
193 views

### What does a positive gradient on a graph of V plotted against I mean in terms of EMF and internal resistance?

According to the equation $V = E-Ir$, the gradient of a graph of $V$ against $I$ should be $-r$ (internal resistance) and the Y intercept should be the EMF. Am I right? In an experiment I used a ...
65 views

### Is Joule heating only between charged particles?

The Wikipedia page for Joule heating explains "It is now known that Joule heating is caused by interactions between the moving particles that form the current (usually, but not always, electrons) and ...
317 views

### Non-conservative Electric Field

I was watching this video from Walter Lewin and while watching these two videos, I noticed there is a "contradiction" in what he is doing. All links direct you exactly to where he begins, so you don't ...
172 views

### Fundamentality of voltage to current

From Ohm's Law : Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. I would like to know if ...
592 views

### Why does the potential drop across a battery and resistor equal the emf of the battery?

In this diagram you can see the potential difference across the battery and resistor is the same as the pd created by the battery (the battery and resistor are representing a battery with internal ...
1k views

### Is it possible to mathematically derive the formula for resistance?

Resistance is given by $\rho L/A$, where $\rho$ is the material constant, $L$ is the length, and $A$ is the area. Is there any way that this can be derived mathematically, or is the only way ...
1k views

### What defines the brightness of a bulb?

So I have a question. There are three identical bulbs, 2 of them are connected in parallel and the third is basically in series, on the same circuit. If the one of the lamps in parallel breaks, what ...
2k views

### Resistor circuit that isn't parallel or series

What's the equivalent resistance in this circuit (between points A and B)?
401 views

### General integral to find resistance

My question is: is there a simple and truly general equation for the resistance between two electrical equipotential surfaces?. Obviously, if so, what is it, and if not, why? It would be very ...
883 views

### As ISA Practical - Resistors in Parallel [duplicate]

Possible Duplicate: Current against the inverse of resistance graph, I = V/R +c How would you set up a circuit with a fixed resistor in parallel with a variable one. We are told to measure ...
351 views

### How can I measure the conductivity of a copper rod?

I would like to perform an experiment to measure the conductivity of a copper rod. What device can I use to perform to experiment? is there such a thing as a conductivity meter? All i found was an ...
1k views

### how calculate resistance between two points for arbitrary resistor grid?

I need to calculate resistance in an electrical grid. Grid is a graph. Edges of a graph are resistors. How calculate resistance between any two vertexes for arbitrary graph? I know Kirchoff law and ...
1k views

### Internal resistance V=IR circuit question [closed]

I don't know how to resolve this problem. A complete circuit consists of a 18,0 V battery (internal resistance r) and a resistor R. The terminal voltage of the circuit is 15,8 V and the current is ...
2k views

### Current against the inverse of resistance graph, $I = V/R +c$

If I have a plot of current ($y$ axis) against 1/Resistance ($x$ axis). The circuit it is measured from is a simply 2 resistors connected in parallel to battery, where the potential across the ...
347 views

### Does power from a resistor perform work or heat transfer?

Let's say I have a cylindrical piston filled with air and fitted with an electrical resistor. The resistor has a current going across it and a voltage for a certain amount of time. My system would be ...
832 views

### Total Resistance of Infinite Resistor Grid?

The problem of the infinite resistor grid is very common. The solution for the resistance between any 2 nodes in an infinite resistor lattice is all over the internet. My question is somewhat similar ...
Suppose we have a cylindrical resistor, with resistance given by $R=\rho\cdot l/(\pi r^2)$ Let $d$ be the distance between two points in the interior of the resistor and let $r\gg d\gg l$. Ie. it is ...