What color bands would have to be on a resistor to bring 50volts dc down to 12 volts?

Question

What color bands would have to be on a resistor to bring 50volts dc down to 12 volts?

Answer 1

Acording to OHMs law,

V=IR

V = Voltage, I = Current, R = Resistance

Voltage is measured in Volts (v)

Current is measured in Amps (a)

Resistance is measuered in Ohms (ohms)

So to go from 50V to 12V you need to increase the resistance (which you seem to know already).

However, you need to know the current in order to correctly determine the resistance.

If we choose 1 as the current you will get the following:

12V = 1 * R

12V / 1 = R

R = 1 (ohm)

So you will need a 1ohm resistor in the example above.

Another Example:

12V = 3a * R

R = 4ohms

In case you didnt know, im using the formula (R = V/I) which is a variation of Ohms law. V = I*R and R = V/I are algebraically equal.

You can look at the resistor color codes link I found after you do your calculations.

Hope this helps.

Answer 2

The resistance value required depends on the current flowing through it - in other words, the circuit that's it's being placed into.

To drop 38 volts at a 1 milliamp current flow, a lower value will be required than in a circuit where the current through it is 1 microamp.