A series circuit consists of three resistors with voltage readings of 40V, 80V, and 100V. What is the total source voltage?

To determine the total source voltage in a series circuit, you add together the individual voltage readings across each resistor. In this case, the voltage readings are 40V, 80V, and 100V.

When you sum these voltages, you get:

40V + 80V + 100V = 220V.

In a series configuration, the same current flows through all components, which results in the total voltage being the sum of the voltages across each component. Therefore, since you have correctly calculated the total source voltage as 220V, it confirms that D is indeed the appropriate answer.

The concept revolves around the fundamental principle of series circuits, where voltages add up while the current remains constant throughout the circuit. This principle is essential for understanding how series circuits operate in real-world applications, making it vital knowledge for anyone involved in biomedical equipment and circuitry.