Definition of electric potential difference
المؤلف:
المؤسسة العامة للتعليم الفني والتدريب المهني
المصدر:
مقدمة عن علم الكهربية الساكنة
الجزء والصفحة:
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15-2-2017
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Definition of electric potential difference
We define the potential difference between two points A and B as the work done by an external agent in moving a test charge qo from A to B i.e.
VB-VA = WAB / qo
The unit of the potential difference is (Joule/Coulomb) which is known as Volt (V)
Notice
Since the work may be (a) positive i.e VB > VA
(b) negative i.e VB < VA
(c) zero i.e VB = VA
You should remember that the work equals
• If 0 < θ < 90 ⇒ cos θ is +ve and therefore the W is +ve
• If 90 < θ < 180 ⇒ cos θ is -ve and therefore W is –ve
• If θ = 90 between Fex and l ⇒ therefore W is zero
The potential difference is independent on the path between A and B. Since the work (WAB) done to move a test charge qo from A to B is independent on the path, otherwise the work is not a scalar quantity.
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