Electric Field Calculator
What is an Electric Field?
Imagine a campfire. The closer you stand to the fire, the more heat you feel. The fire radiates "energy" into the space around it.
An electric charge is similar. It changes the space around it, creating an invisible "aura" called an Electric Field ($E$). If you place another charge (a "Test Charge") inside this field, it will feel a force pushing or pulling it.
- Positive Charge (+): Field lines point Outward (Repelling a positive test charge).
- Negative Charge (-): Field lines point Inward (Attracting a positive test charge).
The Point Charge Formula
To calculate the strength of the field at a specific distance from the charge, we use Coulomb's Constant.
- E: Electric Field Strength (Newtons per Coulomb, N/C).
- k: Coulomb's Constant ($8.99 \times 10^9$).
- Q: The Charge (Coulombs).
- r: Distance from the charge (Meters).
The Inverse Square Law
Just like Gravity and Sound, Electric Fields follow the Inverse Square Law. The field gets weak very quickly as you move away.
- If you double the distance ($2r$), the field becomes 1/4th as strong.
- If you triple the distance ($3r$), the field becomes 1/9th as strong.
This is why you are safe from high-voltage power lines as long as you are a few meters away, but touching them is fatal.
Electric Field vs. Electric Force
This is the most common confusion in physics class. What is the difference between $E$ and $F$?
• Electric Field ($E$): Describes the environment created by ONE charge. It exists even if nothing else is there. (Like the heat from a fire).
• Electric Force ($F$): Describes the interaction between TWO charges. It only exists when a second charge enters the field. (Like getting burned by the fire).
Superposition Principle
What if you have two charges? Or three?
The total electric field at any point is simply the Vector Sum of the fields created by each individual charge. This is called Superposition. You calculate the field for Charge A, then for Charge B, and add them together (accounting for direction).