Massachusetts Institute of Technology
Sign in

MIT Physics Demo -- Back "emf" in a Large Solenoid

A large solenoid is connected to DC power through a knife switch. When the switch is closed, the current builds up to approximately 30 amps. When the switch is opened, the solenoid attempts to keep the current flowing, creating a huge emf which ionizes the air in a huge spark.

Read more about inductors and emf.

Comments (1)

The phrase "solenoid attempts to keep the current flowing" is not very descriptive and somewhat incorrect. Once the current in the inductor reaches a steady 30 amps the magnetic field formed around the solenoid is stable. When the power source is removed the field collapses at very high rate of speed. This very fast moving magnetic field causes a reverse emf in the coil that creates the spark. -RH

Posted almost 8 years by Anonymous User

You need to log in, in order to post comments.

Created
April 09, 2008 13:34
Category
Tags
License
Creative Commons Attribution-NonCommercial (What is this?)
Additional Files


Viewed
69035 times

More from MIT Department of Physics Technical Services Group

Physics Demo -- Magnetic Motor

Physics Demo -- Magnetic Motor

Added over 8 years ago | 00:01:29 | 76904 views

Dissectible Capacitor

Dissectible Capacitor

Added over 7 years ago | 00:02:54 | 49839 views

Cloud Chamber

Cloud Chamber

Added over 7 years ago | 00:02:36 | 91641 views

Coupled Air Carts

Coupled Air Carts

Added over 7 years ago | 00:07:38 | 52969 views

Soap Film Oscillation

Soap Film Oscillation

Added 7 years ago | 00:04:27 | 49410 views

The Wimshurst Machine

The Wimshurst Machine

Added over 6 years ago | 00:02:33 | 48145 views