Electrical Engineering ⇒ Topic : Electric Potential Difference

Sunita
 
Electric Potential Difference In practice, we are more concerned with potential difference between two points rather than their tabsolute potentials. The potential difference (p.d.) between two points may be defined as under
FIGURE (A) The potential difference between two points is the amount of work done in moving a unit positive charge (i.e. + 1C) from the point of lower potential to the point of higher potential.Consider two points A and B in the electric field of a charge +Q as shown in Fig. 5.23. Let V_{2} and V_{1} be the absolute potentials at A and B respectively. Clearly, V_{2} > V_{1}. The potential V_{1} at B means that V_{1} joules of work has been done in bringing a unit positive charge from infinity to point B. Let the extra work done to bring the unit positive charge from B to A be W joules. Potential at A = V_{1} + W P.D. between A and B = (V_{1} + W)  V_{1} or V_{2} V_{1} = W = W .D. to move + 1C from B to A Fig. (A). The SI unit of potential difference is volt and may be defined as under The p.d. between two points is 1 V if 1 joule of work is done in bringing a unit positive charge (i.e. +1 C) from the point of lower potential to the point of higher potential. Thus when we say that p.d. between two points is 5 volts, it simply means that 5 joules of work will have to be done to bring +1C of charge from the point of lower potential to the point of higher potential. Conversely, 5 joules of work or energy will be released if + 1 C charge moves from the point of higher potential to the point of lower potential  
 
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