UPSC General Studies Sample Paper General Studies Sample Paper-8

  • question_answer
    Which of the following is/are necessary condition(s) for the flow of electric current?          
    1. Current can flow only by the movement of electrons.                                
    2. There has to be a voltage difference between two points for current to flow between them.       
    3. Electrons have to travel the entire distance between two points for there to be an electric current between them.                                                                             
    Select the correct answer using the codes given below.                                  

    A)  1 and 2           

    B)  2 and 3           

    C)  Only 2             

    D)  None of, these   

    Correct Answer: C

    Solution :

    [c] Current is caused by the flow of charge. Charge can be due to electrons (as in a circuit) or due to ions (in an electrolyte). Although voltage difference (potential difference) is required for there to be a current flow, it need not be between the two given points, e.g. in a straight wire, current will flow if there is a voltage difference between the end points, but any two points in the middle will not have a voltage difference (assuming zero resistance), even though current flows between them. Current is measured in Amperes and is equal to the amount of charge flowing per second. However, electrons need not travel the entire distance of the circuit for there to be a current. Infact, in a normal circuit all electrons are moving but only in their limited vicinity.

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