Field of Several Charges

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 6 of 51.

The field of several charges is the vector sum of the fields each one makes at the point.

Two charges and a point P

Draw each field, add the parts along each axis, and the size is

$E = \sqrt{E_x^2 + E_y^2}$

Where the fields are equal and opposite, the total field is zero.

Challenge

Q₁ = + $9\ \mathrm{nC}$ sits $0.3\ \mathrm{m}$ to the left of point P, and a negative charge Q₂ of size $4\ \mathrm{nC}$ sits $0.2\ \mathrm{m}$ above P. How strong is the electric field $e$ at P?

Try it yourself

Solve for $E$

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Electricity and Magnetism

1Electric Charge and Force

Electric Charge Coulomb's Law Several Charges Recap - Charges in a Line

4Charged Conductors

The Charged Sphere Connecting Spheres Recap - Beam Between Plates

7Real Batteries

Internal Resistance The Variable Resistor Ammeters and Voltmeters Recap - Flashlight

10Magnetic Fields

Magnets and Magnetic Fields Field of a Wire Loops and Solenoids Recap - Electromagnet

2The Electric Field

The Electric FieldField of Several ChargesThe Uniform Field A Charge in a Uniform Field Recap - Stopping a Proton

5Capacitors

The Capacitor Combining Capacitors Changing a Capacitor Recap - Camera Flash

8Kirchhoff's Laws

The Junction Rule The Loop Rule Solving Two Loops Recap - Charging a Battery

11Magnetic Forces

Force on a Moving Charge Circles in a Field Force on a Wire Two Parallel Wires Recap - Current Balance

3Energy and Potential

Electric Potential Energy Electric Potential Field and Potential Recap - Accelerating Ions

6Current and Resistance

Current and Voltage Resistance and Ohm's Law Series and Parallel Electric Power Recap - Fairy Lights

9Capacitors in Circuits

A Capacitor in a Circuit Charging a Capacitor Discharging a Capacitor Recap - Defibrillator

12Induction

A Rod Moving in a Field Magnetic Flux Faraday's Law Lenz's Law Recap - Generator