CBSE Class 10 Science 2015 Term I Set 1

Question : 23

Total: 36

Study the following current-time graphs from two different sources:

(i) Use above graphs to list two differences between the current in the two cases.
(ii) Name the type of current in the two cases.
(iii) Identify one source each for these currents.
(iv) What is meant by the statement that "the frequency of current in India is 50Hz′′ ?

Solution:

(i)

I	II
Graph (I) shows Direct Current (D.C.)	Graph (II) shows Alternating Current (A.C.)
The current (I) flows in one direction only. It is called a direct current. The magnitude and direction of flow of current remains the same.	The current (II) reverses direction after equal intervals of time. It is called alternating current. The magnitude and direction of current change continuously at definite intervals of time.
The magnitude of current in (I) does not become zero with the passage of time.	The magnitude of (II) becomes zero after a regular time interval.

(ii) (I) → Direct Current (D.C.)
(II) → Alternating Current (A.C.)
(iii) Source of D.C. → a cell, battery, solar cell, D.C. generator
Source of A.C. → A.C. generator.
(iv) 'The frequency of current in India is 50 Hz′ means the direction of current in India changes 50 times in 1 second.

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