Electric Potential
Electric
Potential
Property
Effect or strength of a charge
Effect of a charged body can vary with the distance from the charged body and also
by the amount of charge on the charged body.
Movement of charge due to Electric Potential Difference
Given are two identical Metallic spheres A and B which are connected by a wire. Both spheres are given
8 electrons
Conclusions:
a) Electrons flow from lower to higher potential.
b) Current flows from higher to lower potential.
c) Charge only flows when there is electric potential difference.
Relation between Electric Current and Electric Potential Difference
Consider two wires AB and CD. An electric potential difference has been established across it. Across AB
a small potential difference has been established and across CD, a greater potential difference has been
established.
As potential difference across CD is more, electron move faster in CD
We know that electric current = charge flowing per unit time (q/t) through cross-section of conductor.
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 ∞
1
𝑇𝑖𝑚𝑒
∞ 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒
(Q is same in both cases)
∴ Current ∞ potential difference
Provided physics conditions such as length, temperature, areas of cross-section and material of
conductor should remain constant or in other words resistance of wire should remain constant.
Ohm’s Law
If there is no change in the physics condition of the conductor then current I flowing through the
conductor is directly proportional to the potential difference V across it.
∴𝐼∞𝑉
𝑉
𝐼
= 𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡 (𝑅)
Where R is the resistance of the conductor
Unit of Resistance: volt/ampere or ohm (Ω)
Circuit diagram of Ohm’s Law