A Rod Moving in a Field

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 47 of 51.

A rod of length L moving at speed v across a field B is a battery with

$\varepsilon = BLv$

This is induction.

A rod on rails

On rails joined by R, a current $I = \frac{\varepsilon}{R}$ flows, and the rod feels $F = BIL$ against its motion.

Challenge

A rod $0.4\ \mathrm{m}$ long slides at $3\ \mathrm{m/s}$ along rails through a $0.5\ \mathrm{T}$ field at right angles to it. The rails are joined by a $2\ \mathrm{\Omega }$ resistor. What current $I$ flows?

Try it yourself

Physics diagram: bregion, rails, vec; arrows v

Solve for $I$

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 FieldMagnetic Flux Faraday's Law Lenz's Law Recap - Generator