How many volts does it take to overcome 50 ohms

Question

I have a small LED light and I measured the resistance with my multimeter. It said that my light has a resistance of fifty ohms. My question is how many volts does it take to overcome this much resistance?

Answer 1

Resistance measurements on an LED are useless, as the device is very non-linear.

LEDs require a current source and have a voltage drop of about 2 to 3 volts, and that should be specified.

You run the LED from a voltage of 6 volts or higher via a resistor, which gives you a sort of current source. If you want 20 mA to flow through the LED, which is typical, you calculate the resistor value as follows:

Vb is the battery voltage

Vf is the LED voltage, around 2-3 volts

If is the LED current, usually 10 or 20 mA

R = (Vb-Vf) / If

.

Answer 2

it's not a matter of overcoming the resistance. if you connect a small voltage, you'll get a small current. big voltage, big current.

you don't want to put too much current through the LED and you also need enough voltage to get over the band gap so light is produced. usually one or two AA batteries will do the trick, and it does matter which direction the current flows.