Final answer:
An ohmmeter measures resistance based on Ohm's law, applying a known voltage and measuring current to calculate resistance, which is displayed with hash marks on the scale.
Step-by-step explanation:
An ohmmeter is a tool used to measure resistance in an electronic component or circuit. The ohmmeter function is based on Ohm's law, which states that the voltage (V) across a resistor is equal to the product of the current (I) flowing through it and its resistance (R). Hence, the ohmmeter applies a known voltage to a resistor, measures the resulting current, and then calculates the resistance by rearranging Ohm's law to R = V/I. Modern digital ohmmeters typically display the measured resistance directly, simplifying the process of taking resistance measurements. The hash marks on an ohmmeter's display or scale represent specific resistance values that are typically defined by the numerical markings or whole numbers on either side of these hash marks.