Lenz's Law

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 50 of 51.

Lenz's law: the induced current opposes the change in flux that made it.

A frame entering a field

Flux growing: the current's field points against it. Flux shrinking: along it. Opposing the change is energy conservation.

Challenge

A square frame with $0.2\ \mathrm{m}$ sides and a resistance of $0.5\ \mathrm{\Omega }$ moves to the right at $2\ \mathrm{m/s}$ into a $0.5\ \mathrm{T}$ field. While it goes in, draw the magnetic force on the frame, then find how big it is, $F$ .

Try it yourself

Physics diagram: bregion, loop, vec; arrows v

Solve for $F$

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 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 LawLenz's LawRecap - Generator