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Overall, there are two types of electric currents- Alternating current (AC) and Direct current(DC). In AC, the current moves back and forth at regular intervals; the current changes direction approximately 50-60 times per second. In DC, the direction of the flowing current is the same throughout the circuit, and the electrons move from the negative terminal to the positive terminal.
Alternating Current
Alternating current is a type of electric current that changes its voltage and directions at regular intervals. The change occurs several times in a single second.
Alternating current is used to transmit electricity over long distances of less than 1000 km. If the distance is extra-long, meaning more than 1000 km, the electricity is then transmitted via direct current.
Alternating current is the type of electricity that is cheaper to generate when compared to direct current. Moreover, the AC’s energy loss during transmission in the form of heat is also considered lesser than that of DC’s.
Direct current
It is a type of current that has its current flow in a single direction only. Here, the electrons flow from the negative pole to the positive pole and from a high-density area to a lower density electron area.
The direct current is produced by the batteries, solar panels, windmills and fuel cells. All of these have two terminals: one is positive, and the other is negative, which allows for a constant flow of electrons in a single direction.
Properties of AC and DC in Terms of Usage
It is difficult to change the voltage of a DC when compared to an AC. So AC is used to transmit high voltage electricity rather than DC.
Although AC is used for long-distance transmissions of electricity, the HVDC- High Voltage Direct Current is used for extra long distances, as it proves to be more efficient and beneficial than AC. These properties of AC and DC make the supply and usage manageable for the power plants.
DC is used in any electronic device that requires a battery acting as a power source. Devices that need charging, like phones and laptops, also use DC batteries. This is why they come with AC adapters that convert the alternating current from the plugs/electrical outlets to direct current so that the DC battery is recharged once again.
The AC is generated and distributed by the large power stations in the city for the use of households and offices. The power in the outlets of electricity in one’s homes provides AC power because it is easier to transmit them.
The AC power can be transmitted at long distances at high voltages. These voltages are taken down at the end destination with the help of transformers, which then distribute the low voltage electricity to the respective customers/areas.
Resistance in wires reduces the amount of energy that can be transmitted, so to minimise the loss of energy, voltages are taken up, meaning the voltage is increased for long-distance travelling in AC. This helps reduce pollution as lesser fuel is used to generate more electricity.
The DC is used in electric or hybrid cars, as changing the speed of a DC electric motor is considered to be much easier than an AC motor. AC is used in these motors to recharge the batteries present in the cars.
Differences between AC and DC in Terms of Safety
The table below will provide an idea of how severe and hazardous an electric current of different intensities affects the human body.
AC | DC | Effects |
0.4 mA | 1mA | Slight prickle in the skin |
1-10mA | 5.2-62mA | Painful sensations in the body |
10-16mA | 76mA | Releasing the grip will be hard; paralysing of arms |
23-30mA | 90mA | Breathing becomes difficult; Respiratory paralysis occurs |
75-250mA | 500mA | The heart starts getting affected; Ventricular fibrillation- low blood pressure, consciousness is lost and eventually leads to death. |
The information above suggests that although AC and DC are both life-threatening, the DC needs to be of higher altitude than the AC for similar effects. This is one of the major differences between the AC and DC that makes DC more tolerable and less hazardous than AC.
The conclusion
There are two types of electric currents- Alternating current (AC) and Direct current (DC). In AC, the current moves back and forth at regular intervals. In a direct current, the current flows in a single direction only. DC batteries have two terminals: one is positive and the other is negative, which allows for a constant flow of electrons in a single direction. It is difficult to change the voltage of a DC when compared to an AC. So AC is used to transmit high voltage electricity rather than DC; the HVDC- High Voltage Direct Current is used for extra long distances, as it proves to be more efficient and beneficial than AC.
