Difference Between Multimeter and Ohmmeter

Multimeters and ohmmeters are common electrical testing devices used by electricians and DIY enthusiasts to measure electrical properties such as voltage, current, and resistance. Both of these devices are important tools for troubleshooting electrical circuits and diagnosing faults. However, they are not the same, and there are some key differences between them that we will discuss in this article.

What is a Multimeter?

A multimeter, also known as a volt-ohm meter or VOM, is an electronic measuring instrument that combines several functions into one unit. It typically measures voltage, current, and resistance, and sometimes includes additional functions like capacitance, frequency, and temperature. Multimeters are designed to be versatile and capable of measuring different electrical properties in a variety of settings.

Multimeters come in different types, such as analog and digital multimeters. Analog multimeters use a needle to indicate the measured value on a scale, while digital multimeters display the value on a screen using numeric digits. Digital multimeters are more common nowadays due to their accuracy and ease of use.

What is an Ohmmeter?

An ohmmeter is a type of electrical testing device that measures resistance. It is specifically designed to measure the electrical resistance of a circuit, component, or wire. Ohmmeters work by applying a small voltage across the component or circuit and measuring the current that flows through it. Using Ohm's law, the ohmmeter calculates the resistance of the circuit.

Unlike multimeters, ohmmeters only measure resistance and do not measure voltage or current. Ohmmeters are mainly used for testing resistors, fuses, and other components that are designed to have a specific resistance. Ohmmeters come in different types, such as analog and digital ohmmeters. Analog ohmmeters use a needle to indicate the measured value on a scale, while digital ohmmeters display the value on a screen using numeric digits.

Differences Between Multimeter and Ohmmeter

  1. Functionality: The main difference between multimeters and ohmmeters is their functionality. Multimeters are designed to measure voltage, current, and resistance, whereas ohmmeters are designed to measure only resistance. While multimeters can measure resistance, they are not as accurate as ohmmeters, which are specifically designed for that purpose.

  2. Accuracy: Ohmmeters are generally more accurate than multimeters when it comes to measuring resistance. This is because ohmmeters are designed specifically for that purpose, whereas multimeters are designed to measure multiple electrical properties, which can affect their accuracy.

  3. Range: Multimeters have a wider range of measurement capabilities than ohmmeters. They can measure a wide range of voltage, current, and resistance values, making them versatile and useful in many different electrical applications. Ohmmeters, on the other hand, are limited to measuring resistance within a specific range, typically from a few ohms to a few megaohms.

  4. Display: The way the measurement results are displayed is different between multimeters and ohmmeters. Multimeters typically display the results on a screen using numeric digits, whereas ohmmeters can display the results using either a scale and a needle or numeric digits.

  5. Cost: Ohmmeters are generally cheaper than multimeters because they are designed for a specific purpose, whereas multimeters are more versatile and can measure multiple electrical properties.

When to Use a Multimeter vs. an Ohmmeter Multimeters are useful for a wide range of electrical applications, including measuring voltage, current, and resistance. They are particularly useful for diagnosing faults in electrical circuits, testing batteries, and checking the continuity of wires and cables.

Ohmmeters are best used for measuring the resistance of components, such as resistors and fuses. They are also useful for checking for short circuits and open circuits in electrical circuits. Ohmmeters can help identify whether a component is working properly or not, by measuring the resistance of the component and comparing it to its expected value.

It is important to note that both multimeters and ohmmeters have their own limitations. For example, multimeters cannot measure resistance in a circuit that is powered, as the current flowing through the circuit can affect the accuracy of the measurement. Similarly, ohmmeters cannot measure voltage or current, which may be necessary in some situations.

Conclusion In summary, multimeters and ohmmeters are both important electrical testing devices that are used to measure different electrical properties. While multimeters are more versatile and can measure voltage, current, and resistance, ohmmeters are specifically designed to measure resistance and are generally more accurate in doing so. Knowing the differences between these two devices is important when selecting the right tool for a particular job, as using the wrong device can lead to inaccurate measurements and potentially dangerous situations.