What is resistance?

Resistance refers to the degree to which an object opposes the flow of electrical current. It is a fundamental property of materials and is measured in ohms (Ω). When electric current encounters resistance, it converts some of the energy from the current into heat, which is why resistive components in circuits can become warm during operation.

Understanding resistance is essential in electrical engineering and physics, as it affects how circuits function. The higher the resistance, the less current will flow through the material for a given voltage, in accordance with Ohm's Law, which states that voltage equals current times resistance (V = I x R).

The other choices identify different concepts related to electricity but do not describe resistance. Voltage refers to the potential difference that drives current through a circuit, while electric charge flow represents current itself. Potential difference is also closely related to voltage rather than resistance. Thus, the definition of resistance is accurately captured in the first choice, making it the correct answer.