What term describes a material that does not let electrons move easily?

• A. Electrical conductor
• B. Electrical insulator
• C. Semiconductor
• D. Resistor

Answer: (B)

This question tests how easily electrons can move through a material. A material that does not let electrons move easily is an electrical insulator. In insulators, electrons are tightly bound to atoms and there are few free charge carriers at normal temperatures, often due to a large energy gap between the valence and conduction bands. That means current is very small and the material resists electrical flow. Rubber, plastic, and glass are common examples.

For contrast, a material that conducts electricity has many free electrons and low resistance, allowing easy electron movement. A semiconductor conducts under certain conditions and with controlled doping, sitting between conductors and insulators. A resistor is a device designed to limit current, not a type of material by itself.