NEIEP Mechanics Practice Exam

Calculate the resistance if the voltage is 24 VDC and the power consumed is 40 watts.

1. 6 Ohms

2. 12 Ohms

3. 14.4 Ohms

4. 20 Ohms

The correct answer is: 14.4 Ohms

To calculate the resistance when voltage and power are given, you can use Ohm's Law and the power formula. The power consumed (P) is related to voltage (V) and resistance (R) through the formula: \[ P = \frac{V^2}{R} \] From this formula, we can rearrange it to solve for resistance: \[ R = \frac{V^2}{P} \] In this scenario, the voltage is 24 volts and the power is 40 watts. Plugging in these values, we find: \[ R = \frac{24^2}{40} \] Calculating \( 24^2 \) gives us 576. Then divided by 40 results in: \[ R = \frac{576}{40} = 14.4 \] Ohms. This calculation confirms that the resistance is indeed 14.4 Ohms. The calculation correctly applies the principles of electrical power, reinforcing the understanding that resistance can be derived directly from voltage and power using the appropriate formulas.