Question

A major difference between AC and DC electricity is in its usefulness to effectively supply electricity to large groups. The best explanation for the difference is which of these statements?

A) DC current can be used in transformers while AC current cannot.

B) AC current can be used in transformers while DC current cannot.

C) AC current fluctuates too much to be used effectively in power generation.

D) DC current fluctuates too much to be used effectively in power generation.

Answer 1

The alternating nature of AC current aloows changes in magnet fields to be used to transform electricity and make it more efficient to transport over long distances. AC current can be used in transfromers while DC current cannot.

Answer 2

B) AC current can be used in transformers while DC current cannot.

Step-by-step explanation:

AC current is used for long distance transportation of electrical energy with amplifying the voltage and reducing the current in the conductors so that there is minimum loss of energy in the form of heat.

The relation between heat energy and electrical current is given by Joule's law as:

`Q=i^2.R.t`

where:

• Q = amount of heat energy generated

• i = current in the conductor

• R = resistance of the conductor

• t = time for which the current flows

The above mentioned variation of current and voltage in the transmission lines of AC is achieved by a device called transformer. It consist of a rectangular shaped steel core common to two of the insulated wire winding of which one side acts as input (primary coil) and the other one acts as secondary (output).

AC i.e. alternating current can only be used in the transformers because they have the continuously varying amplitude which in turn provides the change in flux with respect to the time inducing an emf in the nearby secondary coil of the transformer without any physically moving parts.