ESA Certified Alarm Technician Practice Exam

Which of the following is a cause of resistance in a circuit?

1. The connections

2. The diameter of the wire

3. The type of current used

4. The length of the wire

The correct answer is: The connections

The cause of resistance in a circuit can be attributed to various factors, and one significant factor is the physical characteristics of the wire used in the circuit. The diameter of the wire plays a crucial role in determining resistance; a smaller diameter leads to higher resistance because it restricts the flow of electrons through the wire. Additionally, the length of the wire affects resistance as longer wires provide more material for the electrons to move through, increasing resistance. While the connections in a circuit can introduce resistance if they are poor or corroded, options such as the diameter and length of the wire are directly and quantifiably linked to resistance as described by Ohm's Law. The type of current (AC or DC) does not inherently change the resistance of the circuit itself, but rather how that resistance affects the performance of the circuit. Thus, while the connections might influence total resistance in a circuit due to their quality, the diameter and length of the wire are foundational characteristics that define the inherent resistance of any given circuit element. By understanding these factors, one can better grasp how to manage and mitigate resistance in electrical systems.