Final answer:
The statement regarding the electrical code is true; each terminal should have only one conductor attached. Other true/false statements about electrical principles vary from false to true based on the context given.
Step-by-step explanation:
The statement "The electrical code requires that only one bare conductor is connected to a screw terminal" is true. The National Electrical Code (NEC) specifies that each screw terminal should have a single conductor attached to it to ensure a reliable and safe connection. It's important to follow this code, as an improper connection could lead to electrical failure or hazards such as fires or shock.
Regarding the other statements provided for reference:
- High-voltage wires are indeed held aloft by insulating connectors but are not wrapped in insulating material - they are typically bare, which makes the answer false.
- In a circuit diagram, it is false that the voltage is the same at every point in a given wire if differences in potential are considered, due to potential voltage drops across components.
- When a bar magnet is dropped through a copper tube, it indeed induces an electric current, verifying that statement as true.
- A current can be created in a photoconductive cell from even a single photon strike, making that statement true.
- In cars, a single wire can supply current to electrical devices because the car's metal body acts as a return path for the current, completing the circuit and allowing a single wire to suffice.
- The electric-field lines from a positive point charge do spread out radially and point outward, which is true.
- Charging an object by polarization does not necessarily require contact, which makes the correct answer false.
- To charge a sphere by induction, the sphere must be a conductor and connected to the ground. The need for it to be a conductor is true.