There are many units of measurement related to electricity. Each of these units gives us an understanding of how a circuit works. When we measure these units, we can know the characteristics of a circuit and we can find out if a circuit works correctly or if the components in a circuit are working correctly.
What does frequency mean?
In an electrical circuit, the voltage can be turned on and off. The voltage you are dealing with will determine how a circuit turns on and off. The rate that electricity is switched on and off is called frequency which is measured in Hertz(HZ).
There are two types of voltages. One is called AC (Alternating current) voltage and the other is called DC (Direct current). The difference between these two voltages is that the DC voltage turns on completely and turns off completely. On the other hand AC voltage is constantly turning off and on. Each one of these voltages have their own advantages and disadvantages which is why each one is used for different purposes. For example the voltage that is used to send electricity from power stations to transformers and then to houses is AC voltage because it easier to covert AC voltage than DC and can be transmitted using step transformers whilst DC voltage can not do this. On the other hand, DC voltage is used with electrical appliances that use batteries because with DC, the voltage is either on or off so it will provide a constant signal unlike AC voltage which is turning off and on many times in one second so it can not provide appliances with a constant electrical signal.
AC voltage and DC voltage can both be represented on a frequency graph. The two graphs below show AC and dc voltage represented on a graph.
What do you need to measure frequency?
Measuring frequency is different from measuring resistance but is very similar to measuring voltage. In order to measure frequency you will first need a multimeter, preferably an auto ranging multimeter, similar to the one below.
Most multimeters should come with batteries. But if yours doesn’t then you will need to buy the right batteries for you multimeter.
You will also need a pair of probes, one black and one red. These are used to touch the components you want to find the frequency of.
If you meter came with a calibration certificate, it would be even better – this would ensure that you meter is in good working order and more accurate test results would be achieved. This is not compulsory as you can work out if the meter operates correctly by comparing the readings with another meter.
How can frequency be measured?
It is very simple to measure the frequency of a circuit. Firstly, you need pick up the pair of multimeter probes and then you need to choose what part of the circuit you want to test. When measuring frequency, you have the choice to test at the power source of the circuit or at the electrical load which can be something like a bulb for example. One thing you must do when using the meter probes is making sure the tips of the multimeter probes touch the inside of the wire. You have the option of measuring the frequency at the power source of the circuit or at an electrical load such as a bulb. If you are measuring frequency setting on a normal circuit that does turn on and off very fast you will get a reading of nothing because the frequency setting will only work on circuits that are constantly turning off and on at a very fast speed. The reason for this is that Hertz represents how many times the electricity switches from high to low voltage in one second! If all these requirements are met, you should get a get reading on you meter. For example 7 Hz.
The picture below is a diagram of low and high frequency.(This is not shown on the meter)
LOW FREQUENCY GRAPH
HIGH FREQUENCY GRAPH
The higher frequency graph has more waves and is more compact. On the other hand the lower frequency graph has fewer waves and is more spread out. Each wave represents one hertz and each of these graphs are over a period of a second.
One hertz is equal to once cycle. A cycle occurs when the voltage switches once from high to low. The more amount of cycles that take place in a second, the higher the frequency of electricity.
Is measuring frequency important?
The frequency setting on a multimeter is rarely used compared to the other settings on a multimeter. The reason for this is that you will only need to utilise this setting on special occasions. Measuring frequency is used to obtain specific information about how an electrical circuit operates. It is regularly used during the design of a circuit and when constructing electronics or testing sensors for fast electrical signals. However, in these cases it may be best to buy a different type of multimeter called a graphing meter rather than a normal one.