How To Determine If Current Is AC or DC – 3 Steps

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Electrical current is the flow of electrical particles like ions or electrons through space or an electrical conductor. It can be measured as the number of particles flowing through an area of a conductor during a certain time. The electrical current has two types, alternating current, which has two directions, and the direct current, which has only one direction.

How To Determine a Current Is AC or DC?

  1. Look For Power Source Markings
    Suppose the power source has markings on it like positive and negative signs. In that case, the current generated by the source is a direct current because it means that the current has a polarity which means the current has only one direction. The main difference between the DC and AC is that the DC has only one direction, where it flows from the cathode to the anode.
  2. Grab A DC Voltmeter
    If the power source has no markings, you need to use a DC multimeter to determine whether the current is AC or DC.
  3. Connect The DC Voltmeter
    Connect the voltmeter to the source and observe it; if the voltmeter deflects, it’s a direct current “DC”; otherwise, it’s an alternating current “AC.”

How To Measure a Direct Current “DC”?

  1. Choose A DC Multimeter 
    You have to be sure you are using the correct multimeter type; you should use a multimeter designed to measure a direct current and is fused, so the current doesn’t damage your multimeter.
  2. Prepare Your Multimeter 
    Connect the black-colored probe to the comm port; the black-colored probe’s place never changes; meanwhile, the positive or the red-colored probe is the one that can be tricky; if you connect it to the wrong port, you can burn the multimeter’s fuse. You need to plug the red probe into the port with the label “10a”.
  3. Connect The Multimeter to The Circuit
    Measuring current is not like measuring voltage; you can’t directly connect the multimeter’s probes to the circuit; this can blow the multimeter’s fuse if the current is more than 10 amperes. You need to connect the multimeter as a component in the electrical circuit you want to measure its current. Connect the red probe, the positive lead to the power source’s positive side, and connect the negative lead, which is the black probe, to the circuit. 
  4. Observer The Reading
    The multimeter will show the current reading, and the unit for it is amperes; if the current is below 200 milli-amperes, you can use the other port for the red probe.

How To Measure an Alternating Current “AC”?

  1. Adjust Your Multimeter 
    The positive or the red-colored probe is the one that can be tricky; if you connect it to the wrong port, you can burn the multimeter’s fuse; you need to plug the red probe into the port with the label “10a”, meanwhile, connect the black-colored probe to the comm port, the black-colored probe’s place never changes.
  2. Connect The Multimeter to The Circuit
    Measuring current is not like measuring voltage; you can’t directly connect the multimeter’s probes to the circuit; this can blow the multimeter’s fuse if the current is more than 10 amperes. You need to connect the multimeter as a component in the electrical circuit you want to measure its current. Connect the red probe, the positive lead to the power source’s positive side, and connect the negative lead, which is the black probe, to the circuit. 
  3. Observer The Reading
    The multimeter will show the current reading, and the unit for amperes; if the current is below 200 milli-amperes, you can use the other port for the red probe.

What Is the Difference Between AC and DC?

Alternating Current Direct Current
The alternating current is more preferred for long distances, it can be used between cities, and it doesn’t lose its power. The direct current can not be used for long distances because it losses its power.
The alternating current changes its direction due to the rotating magnets. The direct current doesn’t change its direction due to the steady magnetism, so it flows in one direction.
The general frequency of an alternating current is 50 or 60, however, it can change from one country to another. The direct current has no frequency, which means its frequency is zero.
The current in AC flows in the opposite direction periodically. The current in DC flows only in one steady direction.
Electrons in AC can flow back and forth, which means they can change their direction. Electrons in DC can’t flow in many directions, they can only flow in one direction from negative to positive.

Alternating Current

The alternating current is the most preferred and used in buildings, offices, households, etc. This is because the electrons can change their direction in alternating currents; they can move back and forth, so the current changes direction during regular time intervals. The alternating current first testing was by Faraday’s principle using an electric dynamo generator.

The alternating current can be referred to as the curve line due to its waveform, known as the sine wave, the curved lines represent its electric cycles, and the cycles can be measured per second. The alternating currents are used for long distances because they don’t lose electric power over time.

Direct Current

The direct current is different from the alternating current as it can’t change its direction during regular intervals; the direct current flows only in one direction and has a steady voltage. The direct current is used to charge batteries and supply power to electrical appliances and devices, for example:

  • Flashlights
  • Batteries of Mobile Phones
  • Electric Vehicles 
  • Flat-Screen Televisions

Why Is the AC Not Stored in Batteries Like DC?

Because the AC has two different halves in its cycle, with a negative half and a positive half, the two halves cancel each other. Therefore, the polarity of the alternating current is not constant and changes, so there is no energy supply. When this process continues, the battery life is reduced and can be damaged.

However, you have to know that the batteries don’t store energy in them directly; they store chemical energy, a form of electrical energy. The current starts to pass through when the positive terminal of the AC is connected to the battery’s positive terminal, and the AC negative terminal is connected to the battery’s negative terminal.

What Are The Advantages of AC?

The alternating current has many advantages over the direct current, for example:

  • The alternating current is easy to generate and less expensive than the direct current.
  • The distance an alternating current can cover is way more than the distance a direct current can cover.
  • The loss of electric power in alternating current is less than the one lost in the direct current.

Why Is The Alternating Current More Preferred?

The alternating current is more preferred than the direct current due to two main reasons:

  • The transformers have easy installation when at a long distance because the alternating current doesn’t lose much power compared to the direct current at long distances.
  • The alternating current can be stepped down or stepped up to the required value.

Conclusion

To sum up, to determine which type of electrical current you have, AC or DC, you can look if the power source has markings on it like positive and negative signs, the current generated by the source is a direct current because it means that the current has a polarity which means the current has only one direction. 

The main difference between the DC and AC is that the DC has only one direction, where it flows from the cathode to the anode. In addition, you can use a DC voltmeter to know the electrical current type by connecting the voltmeter to the source and observing it; if the voltmeter deflects, it’s a direct current “DC”; otherwise, it’s an alternating current “AC.”

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