A practical current source is usually represented by

 A practical current source is usually represented by                                                         (GATE-EE-1997)

 A.a resistance in series with a ideal current source 

 B.a resistance in parallel with a ideal current source 

 C.a resistance in parallel with a ideal voltage source 

 D.none of the above.

Ans: B

Explanatory Answer:

The diagrams shown below represents an ideal and practical current sources

Ideal current source

Practical current source

An ideal current source does not exists in practice because there is no current source which can maintain current supplied by it constant even when its terminals are open circuited.Hence a practical current source can be represented as an ideal current source in parallel with an resistance as shown above.This resistance R_s is called internal resistance of source.