Before using electronic devices, it is important to understand the basics of electricity. This includes key ideas like voltage, current, and resistance. Many people have heard these terms but may not fully understand what they mean or how they work. This page gives a simple and clear introduction to these concepts. It explains what voltage is, how it differs from current, and how voltage can be measured safely and correctly.

Voltage is like the pressure that pushes electricity through a wire or circuit. It is measured in a unit called volts, written as V. The higher the voltage, the more electrical energy is pushed through.

Electronic devices are built to work with specific voltage levels. If the voltage is too high, it can damage the internal parts. If the voltage is too low, the device might not work at all. That is why knowing how voltage works is important. It helps you use devices safely and fix problems when they do not work as expected.

Voltage is the force that makes electricity flow. To understand this better, it helps to think of electricity like water. Water flows from a high place to a low place. This is caused by a difference in height. In the same way, electricity flows from high electric potential to low electric potential. This difference is what we call voltage.

Current is the actual flow of electricity. Voltage is the force that pushes this flow through a circuit. You cannot see voltage with your eyes, but it plays a key role in making current move.

The potential difference between two places can be expressed as a voltage. Voltage is the “pressure,” as it were, that makes electricity flow. In physics, voltage can be calculated using Ohm’s Law, which tells us that voltage equals resistance times current.

Multimeters (multi-testers) are used to measure voltage. In addition to voltage, multimeters can perform continuity checks and measure parameters such as current, resistance, temperature, and capacitance. Multimeters come in both analog and digital variants, but digital models are the easiest to use without mistakenly reading values since they display values directly.

You may know that there are two kinds of current: direct, or DC, and alternating, or AC. Direct current flows without any change in the direction or magnitude of the current or in the magnitude of the voltage. A familiar example of this type of current would be a battery. Batteries produce voltage and current in a single direction.
If you connect a miniature bulb to a battery, the bulb will generate a uniform amount of light as long as there’s power remaining in the battery, and that is a characteristic of direct current. Direct current flows in a flat or pulsating waveform.

By contrast, alternating current is characterized by voltage and current whose direction and magnitude vary periodically relative to the zero position. A representative example would be the current supplied by household electrical outlets. The voltage and current vary with a set rhythm in the manner of a sine wave, triangular wave, or pulse wave.

A DC circuit must be connected to the battery’s positive and negative terminals in the proper manner. Some circuits won’t operate properly if the battery is connected backwards.

But with a household electrical outlet, electricity will flow even if you reverse the left and right prongs of the plug. Since electricity in an AC current flows in both directions, the magnitude of the electricity varies moment by moment. These values are known as instantaneous values, and they can be described by values such as the maximum value, minimum value, average value, peak-to-peak value, and RMS value.

Voltage is an indicator of the ability to move electricity. The concept is closely related to other concepts such as potential difference, current, and resistance, so it's important to develop an overall understanding of the subject. To measure voltage, you’ll need a multimeter. Multimeters are easy to use, so be sure to utilize them when you need to measure voltage.