Question

Which of the following is the source of direct current?
A. Cell
B. Electromagnet
C. Bulb
D. Switch

Answer 1

Hint: In direct current source, the electric current (time rate of flow of electric charge) is in one direction. The most primer example of a Direct Current (DC) power supply is an electrochemical cell. A battery is formed by combining two or more cells. Then, a battery also uses Direct current.

Complete answer:
The device that can supply electric current is called the source of electric current. Two types of sources of electric current in general use are: Chemical sources of electric current like cell or battery and the electromagnetic sources of electric current like generators.
The cell is the device that converts chemical energy into electrical energy. Cells are of two types:
(a) Primary cell: It is the device that supplies current as soon as it is assembled. Voltaic cells, Daniel cells, and Dry cells are the examples of primary cells.
(b) Secondary cell: It is a device that needs to be charged before it can be used to supply current. They are also called storage cells or accumulators. Acid cell and Alkali cell are examples of the secondary cells.
Direct Current is a unidirectional flow of electric current. DC power source is mostly used by an electromagnetic cell. On the other hand Electromagnet, switch and bulb use both AC and DC power sources.

So, the correct answer is “Option A”.

Note:
 The usage of DC power supply ranges from charging of batteries to large power supplies. Note that a cell is also a part of the battery. Combination of two or more cells is called a battery. DC sources are not commonly used on a household basis. This is because they have large voltages (like transformers) that are harmful for life.