PASCO EM-8642A Magnetic Force Accessory - Manual (Page 8)

®
M a g n e t ic D e m o n s t r a t io n S y s t e m A b o u t t h e E q u i p m e n t
4
EM-8642A Magnetic Force Accessory
The Magnetic Force Accessory consists of the following components:
• Aluminum eddy current blades (solid, with slots, and with slits) for demonstrating magnetic induction and
magnetic braking
• Mounting rod for supporting the blades or the swing assembly
• Swing assembly for demonstrating the magnetic force on a current-carrying wire
• Aluminum tube (paramagnetic material)
• Glass rod (diamagnetic material)
• Thread for suspending the aluminum tube and glass rod
Eddy Current Theory
Eddy currents are currents induced in a conductor when the conductor is exposed to a changing magnetic field due
to the relative motion of the conductor and the source of the magnetic field, or due to variation of the magnetic
field over time. A circulating flow of electrons will form in the body of the conductor. These circulating eddies of
current generate a magnetic field that opposes the change of the original magnetic field as described by Lenz’s law.
The opposing magnetic fields cause drag forces between the conductor and the magnet. The drag forces cause
“magnetic braking”.
Magnet Positioning
The Variable Gap Magnet may be used in four different free-standing positions or can be mounted on a support
rod. The following diagrams show the various positions. The threaded hole in the base accepts a 1/2” (12.7 mm)
threaded rod (13 thread per inch) such as the PASCO ME-8988 25-cm Stainless Steel Rod. The hole also accepts
non-threaded rods less than 12.7 mm (1/2”) in diameter. The thumbscrew on the side of the base holds the magnet
in position on a non-threaded rod..
Figure: Positions for the Variable Gap Magnet
On support
rod
ME-9355 Large
Base and Rod
ME-8988 25-cm
Stainless Steel Rod
SE-9444 Multi
Clamp
Upright Upside down
On side
On end