Electrical resistance is measured using a device called a multimeter, specifically the ohmmeter function. An ohmmeter is a simple and widely used instrument for measuring resistance in electrical circuits. Here's a step-by-step guide on how to measure electrical resistance using a multimeter:
Note: Before attempting any measurements, ensure that the circuit is disconnected from the power source to avoid accidents or damage to the multimeter.
Select the Resistance (Ohms) Function: Turn on your multimeter and set it to the resistance (ohms) measurement mode. This is usually denoted by the Greek letter omega (Ω), which is the unit of resistance.
Zero the Multimeter: Some multimeters have an option to zero or calibrate the instrument before measurement. If your multimeter has this function, follow the manufacturer's instructions to zero the reading to ensure accurate measurements.
Connect the Test Leads: A typical multimeter comes with two test leads, one red and one black. Insert the red lead into the socket labeled "VΩmA" or "COM" (common) and the black lead into the socket labeled "Ω" or "Ohms."
Set the Range: Select an appropriate resistance range on the multimeter. If you have an idea of the approximate resistance value you expect to measure, set the range accordingly. For instance, if you expect the resistance to be in the kilohm range, choose a kilohm range setting.
Measure the Resistance: Now you can measure the resistance. Touch the two test leads together without any components in between. This is to check if the multimeter reads close to zero (it may not be exactly zero due to the resistance of the test leads themselves). If there is any offset, you can press the "Zero" or "Tare" button to adjust it.
Place the Test Leads Across the Component: Now, place the test leads across the component whose resistance you want to measure. For example, if you want to measure the resistance of a resistor, connect one lead to one end of the resistor and the other lead to the opposite end.
Read the Display: The multimeter will display the resistance value on its screen. If the resistance exceeds the selected range, the display may show "OL" (Overload). In that case, you need to adjust to a higher resistance range.
Take Note of the Value: Once the multimeter stabilizes and provides a reading, take note of the resistance value. Remember to include the unit (ohms, kilohms, or megaohms) as per the multimeter display.
Disconnect and Power Off: After obtaining the resistance measurement, disconnect the test leads from the circuit, and turn off the multimeter.
Remember to follow the safety precautions and guidelines mentioned in the multimeter's user manual. Measuring resistance is a straightforward process, but it's important to handle electrical components and circuits with care to avoid any accidents or damage.