Ham Radio General Class Test 2025 – 400 Free Practice Questions to Pass the Exam

Question: 1 / 545

How many watts of electrical power are used if 400 VDC is supplied to an 800-ohm load?

0.5 watts

200 watts

To determine the power used by an electrical load, we can use the formula that relates voltage (V), current (I), and resistance (R):

Power (P) can be calculated using the formula:

\[ P = \frac{V^2}{R} \]

In this scenario, we are given a voltage of 400 VDC and a resistance of 800 ohms. Plugging these values into the formula provides the calculation:

\[ P = \frac{(400 \, \text{V})^2}{800 \, \Omega} \]

\[ P = \frac{160000 \, \text{V}^2}{800 \, \Omega} \]

\[ P = 200 \, \text{W} \]

This calculation shows that the power consumed by the load is 200 watts.

Understanding power calculations is essential in ham radio and electrical engineering, as it helps ensure that equipment operates efficiently and within its specified power ratings. Here, the other options do not align with the calculated power based on the given voltage and resistance; hence, they do not correctly represent the situation.

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400 watts

3200 watts

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