IGCSE Physics – Electricity Practice Test

Friction is the resistive force that acts when two surfaces slide past each other. It comes from the roughness of the surfaces and the microscopic interactions at the contact, and it opposes the direction of motion, often turning some of the motion’s energy into heat. Since the statement refers to the resistance that appears specifically during motion between surfaces, friction is the correct term.

Electrostatic charge relates to electric forces between charged objects, not to the resistive force of sliding surfaces. A thermistor is a device whose electrical resistance changes with temperature, and an LDR (light-dependent resistor) changes resistance with light. Neither describes the mechanical resistance to motion between surfaces.