What is voltage?

What is voltage? Easy-to-understand explanation of the difference from current and units of measurement

▪ Summary

When using electronic devices, you need to have a clear grasp of current, resistance, voltage, and so on. However, there are many people who only know these words and do not understand them in detail. Here, we will explain in layman's terms what the definition of voltage is, what the difference between current and potential is, and other ways to measure voltage.

■ What does voltage mean?

Voltage is the pressure used to output current. Voltage is measured in volts (V), and the higher the voltage, the more power that passes through an electronic device. However, electronic devices require the proper voltage; too much voltage can cause circuit failures.

Conversely, if the required voltage is insufficient, this may also lead to problems such as circuits not starting and not working. In order to use electronic equipment correctly, as well as to find the point of the problem in the event of a malfunction, it is important to deal with it on the basis of an understanding of the voltage.

■ Difference between voltage and current

As previously described, voltage is the ability to make electricity flow. Since voltage cannot be confirmed directly with the eyes, many people may find it difficult to visualize. In order to understand voltage, let's first understand "What is electricity?" .

Electricity is something that flows as a current. It can be visualized as the flow of water in a river. The water in a river flows from the mountains upstream to the sea downstream. In other words, it flows from a place where the water level is high to a place where the water level is low. The same is true of electricity, which corresponds to the level of water in the water called "potential," and which flows in the form of an electric current from a place of high potential to a place of low potential.

Electricity is similar to water flow

The potential difference between them can be expressed as a voltage. Voltage, so to speak, is the pressure that allows current to flow. In the physical world, this can be shown by Ohm's law (Voltage = resistance x current) to calculate.

Resistance is the resistance to the flow of electricity. Imagine a water pipe; if the pipe is small, the resistance will increase and the water will have a hard time flowing, but the strength of the current will increase. Conversely, the larger the pipe, the easier the water will flow, but the strength of the current will weaken. The same is true for current. Resistance and current are directly proportional to voltage; the higher the resistance and current, the higher the voltage.

■ Voltage measurement methods

To measure voltage, a multimeter is required. In addition to voltage, a multimeter can also check conductance or measure current, resistance, temperature, capacitance, and so on. There are two types of multimeters, analog and digital, and the digital type is easier to use because it uses a numerical display that can't be misread.

To measure voltage with a multimeter, connect the positive and negative test leads and switch the measurement range to voltage. Next, place the test leads at the ends of the DUT. With an analog multimeter, adjust the voltage measurement range starting with the larger number.

If the value does not respond, gradually reduce the measurement range and select within the appropriate range to measure the voltage. If you are using a digital multimeter, some of them will automatically adjust the measurement range, so it will be easier to measure.

▪ Difference between DC and AC

There are two types of current, "direct current" and "alternating current". Direct current is the current that does not change direction, current magnitude, or voltage magnitude when current flows through it. Take the example of something around you, such as a dry cell battery. Dry cell batteries produce unidirectional voltage and current.

When a dry cell battery is connected to a miniature light bulb, the bulb continues to emit light at a constant intensity for as long as there is power remaining, which is a characteristic of direct current. The flow of DC can be in the form of a constant current or a pulsating current and so on.

Example of DC waveform

On the other hand, alternating current is a voltage and current that vary periodically in direction and magnitude with respect to the zero position. A typical example would be household electrical outlets, etc. The flow of voltage and current varies in a certain rhythm, such as sinusoidal waves, triangular waves, pulse waves, and so on. As a result, circuits that use direct current have a specific way of inserting positive and negative batteries. If the positive and negative terminals are reversed, certain circuits will not work properly.

AC Waveform Example

However, even the plugs of household sockets can work properly even if they are swapped left and right. Alternating current is a current that flows alternately, which means that the magnitude of the current changes from moment to moment. This is called an instantaneous value, and can be expressed as a "maximum value", "minimum value", "average value", "peak value", "effective value", and so on, "RMS", etc. can be used to express the value.

■ A multimeter is recommended for voltage measurements.

Voltage is an indication of how much power can be transmitted. Be sure to get the whole picture, not just the voltage, as it has a lot to do with potential difference, current, resistance, etc. If you want to measure voltage, you need a multimeter. Because it is easy to operate, it is highly recommended when you need to measure voltage.