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 q_o from A to B i.e.

V_B-V_A = W_AB / q_o          

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 V_B > V_A

  (b) negative i.e V_B < V_A

    (c) zero i.e V_B = V_A

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 (W_AB) done to move a test charge q_o from A to B is independent on the path, otherwise the work is not a scalar quantity.

مواضيع ذات صلة

Thermal conductivity

Molecular diffusion

Ionic conductivity

The drift speed

Electrical transients

الشرر المقدس

الحقول الكهربية والشرر

الخلق غير المرئي

عجائب الكهرباء

مصادر الطاقة الكهربائية

التيارات الكهربائية التي تجري إلى الابد

النقل الكهربائي وقانون أوم