Final answer:
The statement that high-voltage wires are wrapped in insulating material is option b) false; although they are connected by insulators, the air around them serves as the main insulator. Ceramic insulators are used to prevent current flow down towers, and voltage in a circuit can drop across components.
Step-by-step explanation:
The question pertains to the physical structure and electric properties of high-voltage power transmission systems. Specifically, it addresses whether the high-voltage wires seen on metal-frame towers are wrapped in insulating material and supported by insulating connectors. The correct response to this statement is false. High-voltage power lines are not typically covered with insulating material because the air surrounding them acts as a natural insulator, and adding insulation would be impractical due to the massive lengths of these wires. They are, however, connected to the towers through insulating components, often made of materials like ceramic or glass, to prevent electrical currents from flowing down the towers.
Additionally, when discussing insulators in a power transmission context, examples such as ceramic insulators that provide substantial resistance (>1.00×10¹ Ω) to avoid current leakage are mentioned. It is also noted that insulating materials like wood, although non-conductive under normal circumstances, can conduct electricity when conditions, such as those during a lightning strike, tremendously increase the conductivity of materials. In the context of circuit diagrams, it is false to assume that voltage is the same at every point in a given wire, as voltage can drop across components in a circuit. Finally, electric-field lines from a positive point charge do indeed spread out radially and point away from the charge, making that statement true.