Using Ohm's Law in the form V (volts) = I (amps) x R (ohms), complete the following task: In a circuit with an initial voltage of 120 and 4 different devices (load) totaling 300 ohms, what is the amperage involved? Which of the following correctly answers the question?

Question

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300 ohms = A x 120 volts: A = 300 ohms/120 volts: A = 2.5 amps
120 volts = I x 300 ohms: I = 120 volts/300 ohms: I = 0.4 amps
I = 300 volts/120 ohms: I = 2.5 amps
R = 300 ohms x 120 volts: R = 36,000 amps

Answer 1

To use Ohm's Law to find the current (amperage), we start from the formula:

\[ V = I \times R \]

where:

• \( V \) = voltage (in volts)
• \( I \) = current (in amps)
• \( R \) = resistance (in ohms)

Given:

• \( V = 120 \) volts
• \( R = 300 \) ohms

We can rearrange Ohm's Law to solve for current (\( I \)):

\[ I = \frac{V}{R} \]

Substituting the known values:

\[ I = \frac{120 \text{ volts}}{300 \text{ ohms}} \]

Calculating this gives:

\[ I = 0.4 \text{ amps} \]

Now, let's look at the options provided to determine the correct answer:

1. 300 ohms = A x 120 volts: A = 300 ohms/120 volts: A = 2.5 amps - Incorrect. This calculation is wrong based on Ohm’s Law.

2. 120 volts = I x 300 ohms: I = 120 volts/300 ohms: I = 0.4 amps - Correct. This is the correct calculation using Ohm’s Law.

3. I = 300 volts/120 ohms: I = 2.5 amps - Incorrect. This does not relate to the original question values.

4. R = 300 ohms x 120 volts: R = 36,000 amps - Incorrect. This does not relate to Ohm’s Law properly.

The correct answer is:

120 volts = I x 300 ohms: I = 120 volts/300 ohms: I = 0.4 amps.