Resistance is measured using a unit called "ohms" (symbol: Ω). The most common device used to measure resistance is a digital multimeter. Here's a general overview of how resistance is measured:
Select the Resistance (Ohms) Function: Turn on the digital multimeter (DMM) and set it to the resistance measurement mode. This mode is usually denoted by the symbol of a resistor or the letters "Ω" or "ohms."
Zero the Meter (Optional): Some multimeters have a "zero" or "null" feature to compensate for any resistance introduced by the test leads. If your multimeter has this option, touch the test leads together and press the zero button to nullify the resistance of the leads.
Disconnect the Circuit: If you are measuring resistance in a component or a circuit, make sure the circuit is disconnected and powered off. This is important to ensure accurate measurements and avoid damaging the multimeter.
Connect the Test Leads: Take the two test leads provided with the multimeter. Connect one lead to the "COM" (common) socket, and the other lead to the socket labeled for resistance measurements (often indicated by "Ω").
Measure the Resistance: Now, touch the two test leads to the component or section of the circuit you want to measure. Make sure the leads have good contact with the component's terminals or the circuit connection points.
Read the Display: The multimeter will display the resistance value in ohms (Ω) on its screen. Depending on the resistance range and the quality of the multimeter, the display may show several digits after the decimal point.
Interpret the Reading: If you are measuring a resistor or any fixed component, the reading on the multimeter should be close to the labeled resistance value (considering tolerance). For more complex circuits or components, the resistance measurement can provide valuable information about their condition and functionality.
Remember that resistance is influenced by temperature, and some components may change their resistance as they heat up during operation. Therefore, it's essential to consider the context of the measurement and the conditions under which it is taken. Always handle the multimeter carefully and avoid using it in live circuits or with high voltages to prevent accidents.