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Question
A point charge Q is placed at point 'O' as shown in the figure. Is the potential at point A, i.e. VA, greater, smaller or equal to potential, VB, at point B, when Q is (i) positive, and (ii) negative charge?
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Solution
A positive charge creates a positive potential around it in space while a negative charge creates a negative potential around it.
As we move away from the charge radially, the potential decreases. For positive charge the positive potential decreases and for negative charge negative potential decreases.
(i) If the charge is positive then the potential at point A is more positive than the potential at point B. For example, it can be 6 V at A and 3 V at B. So, if you find the potential difference, it will be 3 V.
VA > VB
(ii) If the charge is negative then the potential at point A is more negative than the potential at point B. For example, it can be -6 V at A and -3 V at B. So, if you find the potential difference, it will be [-6-(-3)]=-3 V
VA < VB
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