Which Gear to Use for Voltage Measurement with a Multimeter
A multimeter is a commonly used circuit measurement tool that can measure parameters such as current, voltage, and resistance. When using a multimeter to measure voltage, we need to select the appropriate range gear based on the magnitude of the measured voltage to ensure accurate measurement.
On a multimeter, there are usually multiple voltage range gears to choose from, such as 2V, 20V, 200V, 600V, etc. Each gear represents the upper limit of the measured voltage. For example, if we want to measure a voltage of 5V, we should choose the 20V gear instead of the 2V gear, because the 2V gear cannot display the accurate value of 5V voltage.
If the measured voltage exceeds the selected range gear, the multimeter will not display accurately. Therefore, before measurement, the appropriate gear should be selected based on the estimated range of the measured voltage.
Reasons and repair methods for inaccurate voltage measurement by multimeter
1. Low battery level: If the battery level of the multimeter is low, it may cause inaccurate measurement results. The solution is to replace the battery with a new one and ensure that the battery polarity is correctly installed.
2. Poor contact: Poor contact between the voltage measurement lead of the multimeter and the tested circuit can also lead to inaccurate measurement results. Check whether the plug and connector of the lead are clean, whether there is corrosion or oxidation. If there is, they should be cleaned or replaced.
3. High internal resistance: The internal resistance of the multimeter itself may also affect the accuracy of voltage measurement. Before measuring voltage, you can short-circuit two leads and determine if the internal resistance is too high by reading the short-circuit current. If it is, you need to repair or replace the multimeter.
4. Temperature impact: Temperature changes in the measuring components of a multimeter may result in inaccurate measurements. When conducting precise voltage measurements, temperature compensation function can be considered, or measurements can be taken after stabilizing the temperature in a laboratory environment.
5. Incorrect operation: Improper operation may also result in inaccurate measurement results. Before measuring, read the user manual of the multimeter and select the appropriate range gear based on the voltage range to be measured.
