Connecting Spheres

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 15 of 51.

Joined by a wire, two spheres share their charge until they are at the same potential:

Q₁ + Q₂ = Q

Q₁ / R₁ = Q₂ / R₂

Two spheres joined by a wire

The bigger sphere gets more charge, but the smaller one has the stronger field at its surface.

Challenge

A metal sphere of radius 0.1 m carries 9 nC. It is joined by a long wire to an uncharged metal sphere of radius 0.2 m. How much charge Q_2 ends up on the bigger sphere?

Try it yourself

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 SphereConnecting SpheresRecap - 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 Field Field of Several Charges The 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