Key relationship
Vpoint=kq/r; Vsystem=Σkqⱼ/rⱼ; Vdipole=kp cosθ/r².
Physics · Class 12
Potential of charges and dipoles
Potentials add as scalars while fields add as vectors. An opposite-charge pair has zero potential on its perpendicular bisector but generally a nonzero field there.
Open the interactive experiment →Potential of charges and dipoles
மின்னழுத்தங்கள் அளவிலிகளாகக் கூடும். இருமுனையின் நடுக்கோட்டில் மின்னழுத்தம் பூஜ்யம்.
Key notes, relationships and model limits
Remember
Potentials add as scalars while fields add as vectors. An opposite-charge pair has zero potential on its perpendicular bisector but generally a nonzero field there.
Common trap
Potential is a signed scalar sum; the electric field is a vector sum. Zero potential need not mean zero field.
Model limits
Potential zero at infinity; pair is exact. Dipole option uses far-field approximation; positive probe height avoids singularity.
What you will learn
Use the controls and plotted relation to explain potential of charges and dipoles.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
For p=2×10⁻⁸ C m at r=1 m, the axial potential is ≈179.8 V and equatorial potential is zero.
Why this matters
The model connects potential of charges and dipoles with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
On the equatorial line of an ideal dipole, potential is?
- Maximum because the two charges are closest to the probe.
- Zero, while its electric field need not be zero.
- Zero potential requires zero field at that point.
Read the explanation
Zero, while its electric field need not be zero.
Course connection: Class XII Chapter 2. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.