What Is The Difference Between AC and DC ?

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Before getting deep dive into the question which is more dangerous and which is more efficient we let’s talk about AC and DC.

What is AC Current?

The AC current changes its polarity and magnitude periodically and continuously with respect to time. The Ac current can be produced with a device named alternator that produces the alternating current.

AC Current

AC Current Circuit Explaination

Let’s Understand the Ac current with the water analogy

Suppose a piston is inserted inside a pipe and connected with a rotating rod as in the pin pic below. Here the piston has two strokes one towards upward and the other towards backward on the upward stroke, the water moves in a clockwise direction and the backward direction the water displaces in an anticlockwise direction so in this way water direction changes its direction periodically with oscillation of the piston.

Waveforms of AC Current

Every Ac Waveforms have a divider line or called the zero voltage line that divides the waveform two halves as the Ac current changes the magnitude and direction periodically so on every one complete cycle it reaches zero volts.

AC Waveform characteristics

Time Period (T)

The total amount of time taken by a waveform to repeat itself or to repeat its one cycle is called time period. You can also say the total amount of time taken by wave form to complete its one complete cycle is called time period.


The rate at which the waveform repeats itself is called frequency or you can say the the number of times the waveform repeats in one second is called frequency.its Si unit is Hertz


Amplitude:-The magnitude of the signal is called amplitude

Types of AC Waveforms

Sine Wave

Square wave

Triangle Wave

Application of AC

  • AC is used for long-distance transmission for Offices and Homes
  • Energy Loss in AC is less so widely used in transmission
  • The AC current can be converted into a high voltage to low voltage and low to high voltage efficiently using the transformer
  • AC power is used in larger applications and appliances like Freezers, AC. Dishwashers, washing machines, Fans, Bulbs.

What is DC Current?

The DC current is a unidirectional flow of current or electric charge unlike AC it does not change the magnitude and polarity with time. The DC current has constant magnitude and direction and as the direction and magnitude not changes so the frequency of DC current is zero. The electrons in DC current flow from high electron density to low electron density.

We can get DC from Ac current using the process called rectification and the device that does this is called a rectifier.

Application of DC current

  • DC current is widely used in small electronic devices and gadgets
  • DC current is not good for long-distance transmission but storage of dc current is easy in form of Battery.
  • DC power is used in Cell phones, laptops, radio and other electronic gadgets
  • DC Current are used in flashlights
  • DC current are used in EV and hybrid cars and automobile

Difference between AC and DC

  • Ac current changes its direction during flow while the DC current does not changes its direction during flow and remains constant.
  • The AC current has a frequency that shows how many times the direction of current flow changes during flow while the frequency of the direct current is zero as it do not change the direction of flow.
  • The power factor of AC is 0 to 1 While DC is Constant Zero.
  • The AC current is generated by the alternator while DC current is generated by Photovoltaic cells, generators and batteries.
  • The AC load can be capacitive, inductive or resistive but the load on DC is always resistive.
  • The DC current graph has a constant line showing magnitude and direction is constant while the AC current can be a sinusoidal wave, square wave or triangular wave.
  • The AC converted into DC using a device named rectifier while the DC converted into AC named inverter.
  • AC is widely used in industrial equipment and consumer electronics like AC, Freezer, Cooler, washing machine, lights, fans While DC is used in electronic gadgets and small devices like clocks, laptops, cell phones, Sensors.
  • Ac can be transmitted over long distance with some loss while DC can be transmitted very long distance with very low loss using HVDC

To know about which current is more dangerous AC or DC: click here