Magnetism
Voltage from conductor motion
- where
- induced voltage (V)
- flux density (T)
- conductor length (m)
- perpendicular velocity (m/s)
Explain this equation
Gives the voltage generated in a straight conductor moving through a magnetic field. It is the simplest picture of how a generator produces voltage.
B is flux density in tesla. l is the length of conductor actually inside the field, in metres. v is its speed at right angles to the field, in metres per second. e is the induced voltage.
As the conductor moves it sweeps out an area of l × v every second, so it cuts flux at B × l × v webers per second. By Faraday's law, that rate of cutting flux is the voltage.
A 2 m conductor moving at 3 m/s through 0.5 T gives 3 V. Double the speed and the voltage doubles. Generators get useful voltages from strong fields, high speeds and many conductors in series.
Watch out: field, conductor and motion must all be at right angles to each other. Use only the length in the field, and only the part of the velocity that cuts across the field.
A moving conductor cuts magnetic flux and develops an emf. Only the length within the field contributes.
This simple form needs mutually perpendicular field, motion and conductor. Other angles require the appropriate perpendicular component.
Enter your values to see the result.
Common mistake
Using total wire length rather than active length.
Limits
Uniform field and mutually perpendicular geometry.
Sources
The tools calculate the displayed equation. They do not automatically choose cable sizes, approve installations, supply current regulatory tables, certify equipment or replace inspection and testing.