Electric Field (Point Charge) Calculator
Field strength due to a point charge.
Formula first
Overview
This equation defines the magnitude of the electric field produced by a stationary point charge in a vacuum. It describes how the field strength is directly proportional to the quantity of charge and decreases according to the inverse square of the distance from that charge.
Symbols
Variables
E = Field Strength, Q = Charge, \epsilon_0 = Permittivity, r = Distance
Apply it well
When To Use
When to use: Apply this formula when calculating the field intensity at a specific point in space surrounding a single, isolated charged particle. It assumes the charge is concentrated at a single point and that the surrounding environment is a vacuum or air, where the permittivity of free space is applicable.
Why it matters: This principle is the cornerstone of electrostatics, explaining how particles exert forces on each other without direct contact. It is essential for engineering electronic sensors, managing high-voltage insulation, and understanding the behavior of subatomic particles in physics research.
Avoid these traps
Common Mistakes
- Using r instead of r².
- Mixing microcoulombs and coulombs.
One free problem
Practice Problem
Calculate the magnitude of the electric field at a point 3.0 meters away from a point charge of 1.0 microCoulomb in a vacuum.
Solve for:
Hint: Convert 1.0 microCoulomb to 10⁻⁶ Coulombs and calculate r² as 9.0.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Halliday, Resnick, and Walker, Fundamentals of Physics, 10th ed.
- Griffiths, David J. Introduction to Electrodynamics, 4th ed.
- Wikipedia: Electric field
- NIST CODATA: Permittivity of vacuum
- NIST CODATA
- Halliday, Resnick, and Walker, Fundamentals of Physics
- Halliday, Resnick, and Walker Fundamentals of Physics
- Wikipedia article Electric field