Difference between AC and DC

Q1

Why can’t AC be stored in batteries instead of DC?

It is important to understand that batteries do not store the energy directly in them. They store electrical energy in the form of chemical energy. The positive terminal of an AC source is connected to the positive terminal of the battery and the negative terminal of an AC source is connected to the negative terminal of the battery. The current starts to flow. But, AC changes its polarity and there is no actual supply of the energy. This is because the positive half cycle cancel outs the negative half cycle. If this process continues, it can damage the battery. Therefore, AC is not stored in batteries.

Q2

What are the advantages of AC over DC?

Following are the advantages of alternating current over direct current:

• AC is less expensive and easy to generate than DC.
• AC can be transmitted across long distances without much energy loss, unlike DC.
• The power loss during transmission in AC is less when compared to DC.

Q3

Why is the use of AC voltage preferred over DC voltage?

There are two reasons why the use of AC voltage is preferred over DC voltage:

• The loss of energy during the transmission in AC voltage is less when compared with the DC voltage and this makes its installations easy when the transformers are at distance.
• AC voltage has the advantage of stepping up and stepping down as per the requirement.

Q4

What is wattless current?

Wattless current is defined as the current in an AC circuit when the average power consumption is zero.

Q5

What will be the value of the power factor in the circuit when it is at resonance?

The value of the power factor in the circuit when it is at resonance will be 1.

Q6

Give reasons for a loss in energy in the transformer.

Following are the reasons because of which there is a loss in energy in the transformer:

• Hysteresis
• Eddy current loss
• Leakage of flux