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:

$\relax Q_{1} + Q_{2} = Q$

$\frac{Q_1}{R_1} = \frac{Q_2}{R_2}$

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 $0.1\ \mathrm{m}$ carries $9\ \mathrm{nC}$ . It is joined by a long wire to an uncharged metal sphere of radius $0.2\ \mathrm{m}$ . How much charge $\relax Q_{2}$ ends up on the bigger sphere?

Try it yourself

Solve for $Q_{2}$

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