ARRL Technician Practice Exam 2025 – Complete Prep Guide

In a typical circuit diagram, the identification of components is crucial for understanding how the circuit operates. Number 4, as represented in your question, specifically refers to the battery, which is a vital component in any circuit, as it provides the necessary voltage and power to drive the current through the circuit.

Batteries are marked in circuit diagrams based on standard conventions, and they are typically represented as a pair of parallel lines, where the longer line indicates the positive terminal and the shorter line indicates the negative terminal. This visual representation helps in quickly identifying the power source in the circuit design.

Capacitors, transformers, and inductors each have their unique functions and symbols in circuit diagrams. Capacitors store electrical energy temporarily, transformers change voltage levels, and inductors store energy in a magnetic field when current flows through them. However, in the context of the question, the emphasis remains on the battery as the power source, making it the correct identification of number 4.