Equivalence of large and small loops around enclosed flux

A laminated iron core is inserted into a large coil of 1532 turns. Two 6 V.D.C. batteries are hooked up to the coil via a knife switch. Two different loops, one about thee times larger than the other, are laid around the coil and connected to a projection galvanometer through either side of a reversing switch. When the coil is powered the needle deflection is identical whichever loop is chosen
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All this equipment is commonly used but I caution you that you may wish to set it up on a cart to the side of the lecture table. E&M fields emanating from equipment in the desk could interfere with a clear result on the experiment. Leave extra time to calibrate equipment as getting the opamp perfectly tuned to give a clear signal can take some time.