How to find out resistance

Then the voltage over the resistor is the difference between your power supply (3V) - voltage over the LED (2V) = 1V. To compute the resistance you do 3 / 30e-3. wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. If a comment is too long you can either edit your answer (generally if it's expanding something already in the answer), or just post more than one comment.I'm not sure what you mean by "degrees". Rearrange the total resistance formula to solve for the unknown resistor. Thank you so much!" It drops.

Your "3V / 30mA = 100 Ohms" is exactly how it should be written.You bring up a good issue with a calculator though. I like the way it's explained here!" Why do we use the difference? Thanks to all authors for creating a page that has been read 1,405,530 times.wikiHow is where trusted research and expert knowledge come together.
You choose a resistor for the difference between supply and "LED voltage".by using a voltmeter in the software the voltage across the LED is 1.9V, I'm guessing that is the voltage drop.Could you explain this sentence a bit more: "To get 30 mA through the resistor (and thus also the LED) your resistor has the be 1V / 30 mA = 33 Ohm." Resistance1 multiplied by resistance 2, divided by sum of resistance 1 and resistance 2.

- P = RI * I

I = V/R . Every day at wikiHow, we work hard to give you access to instructions and information that will help you live a better life, whether it's keeping you safer, healthier, or improving your well-being. wikiHow's There are two ways to hook together electrical components. There's a Kirchhoff's voltage law (KVL) which says that the total voltage of your loop always is zero. I really enjoyed it." Stocks run into resistance (supply) because those traders that bought too late and saw the price go down now want to get out at break even so they sell. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. Textbooks often use "perfect batteries" with zero resistance, but in the real world they do have a small amount of resistance. This is the potential difference across the terminals of the cell when current is flowing in the circuit, it is always less than the e.m.f. A further increase of the voltage will then cause a drastic increase in current.

1 - P = V * I The units of resistance are Ohms which was named after German Physicist Georg Simon Ohm. These parts are then connected in parallel. - R = 75/0.1156 = 648A "This article was very helpful in understanding the equation and calculations needed to get net circuit resistance.

However, your picture implies it's a red LED, so I'm guessing not. If the cross sectional area of the conductor is 10mmsq, calculate the resistance of the conductor. For example, if a series circuit has total resistance 10 ohms, one 7 ohm resistor, and one unknown resistor R, use the formula for total resistance in a series circuit: 10 = 7 + R. Calculators generally don't handle units. However, AC circuits do have a similar quality called reactance which does change with frequency. wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To calculate R we need to know the voltage on the resistance. By using our site, you acknowledge that you have read and understand our Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. If I had written the equation in milliamps and pressed 3/30 on a calculator what would be the units of the answer?Thanks, I guess you have to know the "degrees" off by heart, if your not using a computer. This limits the current through the wire in order to reduce any heating effect which may change the resistivity. First, take a wire and join it with v volt battery, then join a resistance R1 between wire. If you really can’t stand to see another ad again, then please We use cookies to make wikiHow great. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/8e\/Calculate-Total-Resistance-in-Circuits-Step-1-Version-2.jpg\/v4-460px-Calculate-Total-Resistance-in-Circuits-Step-1-Version-2.jpg","bigUrl":"\/images\/thumb\/8\/8e\/Calculate-Total-Resistance-in-Circuits-Step-1-Version-2.jpg\/aid487580-v4-728px-Calculate-Total-Resistance-in-Circuits-Step-1-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"