Name: Dipole in an Electric Field
Uploaded: 2019-07-19
Duration: 11 min 59 s
Description: Dipoles exists everywhere. They apply to both electricity and magnetism in physics. Here in this video, let us explore how an electric dipole interacts with...

Question

Define electric potential. Write its SI unit and give an example in which electric potential is zero, but electric field is not zero and also give an example in which electric potential is non-zero or uniform, but electric field is zero.

Accepted Answer

Electric potential: It is defined as amount of work done per unit test change $i . e V = \frac{W}{q}$ . Its $S . I$ . unit ${JC}^{- 1}$ or Volt

(a) Example for $V = 0$ and $E \neq 0$

Electric potential at point $O$ due to $-q$ and $+ q$ is

$V = V_{1} + V_{2} = \frac{1}{4 π \in_{0}} \frac{- q}{r} + \frac{}{4 π \in_{0}} \frac{q}{r} V = 0$

$i . e$ ., Potential at mid-point of at dipole at due to dipole is zero.ch

Electric field at mid -point of dipole

$E = E_{1} + E_{2} = \frac{1}{4 π \in_{0}} \frac{q}{r^{2}} + \frac{1}{4 π \in_{0}} \frac{q}{r^{2}} \Rightarrow E = 2 . \frac{1}{4 π \in_{0}} \frac{q}{r^{2}} = \frac{2 kq}{r^{2}} i . e ., E \neq 0$

(b) Example for

$E = 0$ but $V \neq 0 \to$ let $ABCD$ be the square of each side a and charge q is at the centre.

$∵$ $OA = OB = OC = CD = \frac{d}{2} = \frac{a}{\sqrt{2}}$

Electric field at point $O$ due to system of four charges

$E = E_{A} + E_{B} - E_{c} - E_{D} (E_{A} = E_{B}, E_{B} = E_{D}) or \Rightarrow E = 0$

And eclectic potential at point $O$ due to system of $4$ Charges.

$V = V_{A} + V_{B} + V_{C} + V_{D} = \frac{1}{4 π \in_{0}} \frac{q}{OA} + \frac{1}{4 π \in_{0}} \frac{q}{OB} + \frac{1}{4 π \in_{0}} \frac{q}{OC} + \frac{1}{4 π \in_{0}} \frac{q}{OD} = 4 \frac{1}{4 π \in_{0}} \frac{q \sqrt{2}}{a} ∴ V = 4 v [Where v = 4 \sqrt{2} \frac{kq}{a}] i . e ., V \neq 0 .$

Define electric potential. Write its SI unit and give an example in which electric potential is zero, but electric field is not zero and also give an example in which electric potential is non-zero or uniform, but electric field is zero.

Important Questions on Electric Potential

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