Current-time graphs from two different sources are shown in the following diagrams. Now answer the following questions.
(1) Name the type of current shown by graph A and graph B.
(ii) Name any one source of the current shown by graph A and graph B.
(iii) What is the frequency of current in case B?
(iv) Write two difference between the current shown by graphs A and B.
OR
Write one difference between A.C and D.C.
(i) Graph A represents direct current (D.C). Graph B represents alternating current (A.C).
(ii) A dry cell is the source of current shown by Graph A. An A.C generator is the source of current shown by the graph B.
(iii) From graph B, time period, T = 0.02s. Therefore, frequency of current, 
= 50Hz.
(iv)
| Direct Current | Alternating Current |
|---|---|
| The magnitude of direct current is constant and flows in one direction only. | The magnitude of AC changes with time and direction of alternating current reverses periodically. |
| direct current cannot be used for large scale supply of electricity for household purpose. | alternating current is used to run electrical appliance like electric bulb, electric heater, electric iron, refrigerator etc. |
| The frequency of direct current is zero. | Frequency of alternating current in India is 50 Hz. |
Good answer with the graphs.
Also as mentioned on askanydifference website, we can say that a DC current can increase or decrease in magnitude but it can never change its direction.
This is important because we usually think and represent DC current as a stratigh horizontal line only. It can be diagnol also when magnitude of current is changing