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How does a resistor affect the flow of electric current?

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Conductors and insulators in flexible electronics — electronics The development of screen-printable electronic ink for flexible electronics.

A resistor is an electrical component that opposes the flow of electric current within a circuit. It functions by transforming electric energy into heat energy, a process caused by collisions between current-carrying charged particles and the fixed particles that compose the conductor's structure.12

The relationship between the current ( $I$ ), the voltage ( $V$ ), and the resistance ( $R$ ) is defined by Ohm’s law, expressed as:

$V = I R$

Because resistance is the constant of proportionality between voltage and current, a resistor effectively limits the amount of current that flows through a circuit for a given voltage. If the voltage remains constant, increasing the resistance will decrease the current, while removing resistance will increase it.34

Beyond simply opposing current, resistors are essential tools used to protect, operate, and control circuits, such as by dividing voltages or shaping electrical waves to meet specific design requirements.1