Current and voltage are things that we often encounter in our daily life, any electrical product is marked with current and voltage for our use, in the previous article we learned the basic definition of current and voltage, today let's understand how voltage is measured and what is the difference between him and current?
In electrical and electronic circuits, voltage measurement is the basic parameter that needs to be measured. We can measure the voltage between a specific point and a ground wire or a zero-volt line on a circuit.
In a three-phase circuit, if we measure the voltage between any of the phases from the three-phase point to the neutral point, it is called a line-to-ground voltage.
Similarly, if we measure the voltage between any two phases from three phases, it is called a wire-to-line voltage.
The voltage between two points in the system can be measured using a voltmeter. In order to measure voltage, the voltmeter must be connected in parallel with the component to be measured.
One of the leads of the voltmeter must be connected to the first point and one to the second point. Note that voltmeters should not be connected in series.
A voltmeter can also be used to measure the voltage drop of any component or the sum of the voltage drop of two or more components in a circuit. The diagram below shows the voltmeter connection used to measure the voltage across the resistor.
An analog voltmeter works by measuring current through a fixed resistor. Now, according to Ohm's law, the current passing through the resistor is proportional to the voltage or potential difference across the fixed resistor. Thus, we can determine the unknown voltage.
The following diagram shows another example of a voltmeter connection used to measure the voltage of a 9 V battery:
Nowadays, one of the most common ways to measure voltage is by using a multimeter. A multimeter can be analog or digital, but a digital multimeter is the most commonly used because it is more accurate and less costly.
The voltage or potential difference of any device can be simply measured by connecting the probes of the multimeter at the two points where the voltage is to be measured. Use a multimeter to measure the battery voltage as shown in the figure below.
Potentiometers work on the principle of zero balance technology. It measures the voltage by comparing an unknown voltage with a known reference voltage. The potentiometer circuit used to measure the voltage is shown in the figure below.
Other instruments such as oscilloscopes, electrostatic voltmeters can also be used to measure voltage.
The main difference between voltage and current is that voltage is the potential difference between two points of charge in an electric field, whereas current is the flow of charge from one point to another in an electric field.
We can simply say that voltage is the reason for the flow of current, and current is the effect of voltage.
The higher the voltage, the greater the current flowing between the two points. Note that if two points in a circuit are at the same potential, current cannot flow between those points. The magnitude of voltage and current is interdependent (according to Ohm's law).
The table below discusses the other differences between voltage and current.