How to find out resistance

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To get 30 mA through the resistor (and thus also the LED) your resistor has to be 1V / 30 mA = 33 Ohm.You have to take in count the \$V_{F_{typ}}\$ of the LED. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. Series circuits use components connected one after the other, while parallel circuits connect components along parallel branches.

This is derived from the equation V =I R. In the question the value of potential difference (v) is mentioned as 2V, i.e, 2 volts.

Good job."

Is it ok to put units in an equation? How do I calculate the total resistance of the resistors?

Certainly there are LEDs and applications for which this is valid. In this equation (V) appears which is the terminal potential difference, measured in volts (V).

Find out why Close. But usually most of the LEDs have 1.7V drop and that would make the total voltage of the circuit 1.3V and minimum resistance at 43ohms.

If 3 resistances of 3 ohms each are connected in parallel, what will be their total resistance? Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker.

"WikiHow is doing a very good job for those who really have interest and want slight help. - Let's check if it is the same with the other method. I usually run 5mA thru a 20mA LED for indicator use.Is the power coming from a battery?

If so, it is likely worth getting a more efficient LED and running it at a lower current.My second comment is about your equation, "3/0.03 = 100 Ohm". Share. How do I connect a resistor to get the minimum resistance? Adding 1/(1/3+1/3+1/3) will be 1 ohm, since all the resistors are connected in parallel.

We know three resistor values, but how do we find the missing resistor value if no other info is given?

However, AC circuits do have a similar quality called reactance which does change with frequency. If this is relevant to the circuit diagram, the internal resistance is drawn in series with the voltage drop, with a box around them indicating that they are both part of the battery.

The units of resistance are Ohms which was named after German Physicist Georg Simon Ohm. "The formulas of the series and parallel circuits helped me a lot with my circuits assignment." Featured on Meta