First-Year HVAC Service Certification Practice Test 2025 - Free HVAC Service Practice Questions and Study Guide

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If capacitors of 10 mfd, 5 mfd, and 5 mfd are wired in series, what is the total capacitance in mfd?

20 mfd

2 mfd

When capacitors are wired in series, the total capacitance can be calculated using the formula for capacitors in series, which is:

\frac{1}{C_{\text{total}}} = \frac{1}{C_1} + \frac{1}{C_2} + \frac{1}{C_3}

In this case, you have three capacitors with values of 10 mfd, 5 mfd, and 5 mfd. Plugging these values into the series capacitance formula gives:

\frac{1}{C_{\text{total}}} = \frac{1}{10} + \frac{1}{5} + \frac{1}{5}

To combine the fractions, you'll first convert them to a common denominator:

\frac{1}{10} + \frac{2}{10} + \frac{2}{10} = \frac{5}{10} = \frac{1}{2}

Now, taking the reciprocal to find the total capacitance:

C_{\text{total}} = \frac{1}{\frac{1}{2}} = 2 \text{ m

10 mfd

5 mfd

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