Technician: Current Flowing in a Resistor

What is the current flowing through a 24-ohm resistor connected across 240 volts? [T5D09]

A. 24,000 amperes
B. 0.1 amperes
C. 10 amperes
D. 216 amperes

Get out your calculators, because this is a cut-and-dried case of needing to use Ohm’s law.

Ohm’s law defines the relationship beteween voltage, current, and resistance in a circuit.  It looks like this:

V = IR

Where V is voltage, I is current, and R is resistance.  You might see it with and E for Voltage instead of V.  (Old habits die hard!)

All we need to do is substitute in our known values and then solve this simple equation for the current, like this:

240 = (I)(24)

re-arranging, we get:

I = \frac{240}{24}

which reduces to:

I = 10

and we get our answer, C. 10 amperes.

(Photo: https://commons.wikimedia.org/wiki/File:Ohms_law_voltage_source.svg)

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