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Ideal current souce has infinite impedance. What is the reason to have infinite impedance. What is the use of having infinite impedance.  For example,  if ideal current source has 5 Amperes rating and has impedance of 1 ohm it will supply 5 Amperes to the load. And for the same current source,  if it has 1 Megha ohm impedance then also it will supply same 5 Amperes current to the load. Then what is the use of having infinite impedance.

         (Thanks for previous answers. I am completely satisfied with your answers. You are really good expert in the field of electronics)

Thank you.

The above link is an outline of the constant current source concept (both dependent and independent).

The ideal constant current source is only ideal and a rather abstract concept because in reality current sources DO have internal impedance and therefore in real circuits have limitations on them.  

Your example of the ideal 5 amp source connected to a 1 Mohm load would, in theory, develop a voltage across the resistor of 5 million volts.  In practicality that is quite impossible. In the real world the internal resistance of the source would limit the current capability.

So, theory and practice are, in reality, tempered with wisdom and the point of crossover from the ideal to the practical world.

Therefore, let us accept the ideal current source as a mathematical model which helps us understand the theory but leaves us with engineering judgement to know that the real world results will be adjusted due to physical limitations from the ideal.

Hope this helps.  


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Graduate electrical engineer with over 40 years in electronic design, manufacturing, project organization and patent review. Experience in fields of industrial and consumer electronics (audio, video, acoustics, etc.)

IEEE (Institute of Electrical and Electronics Engineers); Senior Life member AES (Audio Engineering Society), Fellow Life member

BSEE University of North Dakota

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