Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

In a series circuit, what happens to the voltage drop across each resistance?

1. It equals zero.

2. It multiplies each resistance.

3. It adds up to equal the source voltage.

4. It remains constant across all loads.

The correct answer is: It adds up to equal the source voltage.

In a series circuit, the voltage drop across each resistor is determined by Ohm's Law, which states that voltage (V) is equal to the product of current (I) and resistance (R). As current flows through each resistor, the voltage drop across each one is proportional to its resistance. The key characteristic of series circuits is that the total voltage supplied by the source is divided among the resistances in the circuit. When you sum the voltage drops across each resistor, this total will always equal the source voltage. This is consistent with the law of conservation of energy, which in this context states that the total energy provided by the voltage source gets used up by all the resistors in the circuit. Therefore, the correct answer highlights that the individual voltage drops across each resistance indeed add up to equal the total voltage provided by the circuit's source.