Questions tagged [ohms-law]

A well known relationship that describes the relationship between Voltage and current through a device's resistance expressed mathematically as V= IR. This formula says that voltage across the device is equal to the current through the device multiplied by the resistance.

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Use battery voltage rating or fully charged voltage?

I am using a 3.7V (18650) battery, but its fully charged voltage is 3.85V. When calculating a resister for an LED circuit, do I use the battery's voltage rating (3.7V) or the fully charged voltage (3....
142 views

Which current should I use to determine the Watt?

I am making a heated blanket and I have some troubles to determine the heat that will be generated. Resistance: Let say, I use this heated cable with a resistance of 0.3 Ohms/m*. If I am using 10m ...
546 views

Best resistance for RED/BLUE 3 lead LED

I have a project where a PCB has been manufactured with an error, where a 3 lead BI color LED (red/blue) has a single resistor to limit the current for both colors. I can fix this by hacking apart the ...
707 views

Finding node voltage of a “Y” resistor network

I am trying to find the voltage at NODE1. My initial approach was to find the current starting from the $15$V source then going through $R_1$ and $R_3$ to ground. Then calculating the current ...
80k views

How can a resistor affect current AND potential at the same time?

Though the resistor is always introduced as one of the most simple components it is the one which makes least sense to me. Ohm's law defines the resistance as$$R = \frac{V}{I}$$ this means that the ...
140 views

Regarding the design of a basic voltage divider

I've just entered the fabulous world of circuitry and was wondering about the design of voltage dividers. I understand their function and formula quit well, but was wondering about the actual ...
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How to understand this circuit?

I'm studying about Ohm's Law, and the following problem perplexed me. The answer is $I_{t} = 11$mA and $U_{r} = 41$V. What I need to find is $U_{t}$ and $I_{t}$. The only thing I've found so ...
217 views

how does ohms law apply in power system

It appears that either all the people over the internet have either not thought about this question or that I am mistaken in my thought somewhere: Confusion appears when I try to apply ohms law to ...
7k views

How do current limiting resistors work between ICs?

In a simple battery+resistor circuit with a fixed voltage, the resistance of a series resistor determines the current flowing through it. But what happens if this resistor is placed between two ICs? (...
2k views

What's the correct term to describe a conductor which doesn't always obey Ohm's law?

Non-ohmic comes to mind, but that gives an impression that the conductor never satisfies Ohm's law. Is there a better term which describes a conductor which might satisfy Ohm's law at certain voltages ...
968 views

Convert transformer resistance data from Watts to Ohm

Short version: How can I convert transformer resistance values from Watts to Ohms? Long version: In PSS/E, transformer resistance can be entered as either per unit values (system base or transformer ...
767 views

What determines a load's current requirements?

Apologies if this question has been asked before. I'm sure it has but hard to find as wording of question may not bring up the duplicate question. Let us say we have a 10 ohm resistor as a load. ...
1k views

Rule of thumb for LED Ballast Resistor

As well all know, using an LED without some sort of current control is a bad idea. One of the most basic types is a simple Ballast Resistor, paired with Ohm's Law. Based on Vin, Vf, and the desired ...
1k views

Ohm's Law and in-series components

I am doing some practice problems based on what I learned today in lecture. However, I am stuck on this problem: ...
2k views

Ohm's law clarification

I am slightly confused about Ohm's law. I understand V = IR, and I did a simple experiment on paper. The results are slightly confusing, so I was hoping someone could tell me if I'm right? First, I ...
3k views

Connecting a parallel port to an Arduino

This is my first Arduino project and while I remember a (tiny) bit of electronics from school I'm struggling to get this working - in fact I've just fried a parallel port PCI card! I'm looking to ...
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Why does the voltage changes in this simple circuit?

I'm beginning to learn electronics, and there's something I just can't grasp. I was told that a high resistance in a circuit would lead to a smaller current passing through it, but the voltage would ...