J6-21.HTML
J6-21: MAGNETIC FIELD IN GAP OF ELECTROMAGNET

PURPOSE: To semi-quantitatively measure the magnetic field in the air gap of a magnet.

DESCRIPTION: Using a magnet with a square yoke, separate the top yoke member, creating two gaps in the yoke. Into one gap place a small search coil; into the other place a non-magnetic shim. As the gap length h is increased the field B(gap) decreases:

B(gap) = mu(0) N i / h,

where N is the number of turns and i is the current in the coil.

SUGGESTIONS:

REFERENCES: (PIRA unknown.) See Demonstration Reference File for further information and derivation of equations.

EQUIPMENT: Demountable transformer, oscilloscope with TV display, variac and search coil.

SETUP TIME: 10 min.


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