Resistors are two-terminal devices that restrict, or resist, the flow of current. The larger the resistor, the less current can flow through it for a given voltage as demonstrated by Ohm's law. Electrons flowing through a resistor collide with material in the resistor body, and it is these collisions that cause electrical resistance.
In this design challenge, we will build a circuit with a 5V source, 6.8 kΩ, and an arbitrary resistor. We will use the concept of voltage division to determine the resistance value of the arbitrary resistor when given a specific voltage drop across it.
Voltage dividers and resistors in series can also be used to control the amount of current that is drawn from a power source.