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Primary and Secondary Coils
SS2409
Specifications
Iron Core length: 3.25" / 8.3cm
Iron Core Dimeter: 7/16" / 12mm
Primary Coil Spindle O.D.: 3/4" / 19mm Primary Coil Spindle I.D.: 1/2" / 13mm
Primary Coil Turns (approx.): 160
Primary Coil Wire Diameter: 20AWG
Secondary Coil Spindle O.D.: 1-3/8" / 35mm
Secondary Coil Spindle I.D.: 1-5/8" / 39mm
Secondary Coil Turns (approx.): 330
Secondary Coil Wire Diameter: 28AWG
Use
This primary and secondary coil set utilizes a soft iron core, primary and secondary coil. The smaller primary
coil set is constructed of larger diameter wire, and is designed so that it will fit inside of the secondary coil. This
coil is designed to demonstrate that a change in current in one coil induces a current in the second coil that is
within the same field due to close proximity. To experiment, construct a simple circuit by attaching the red and
black connectors on the primary coil (inside coil) to a 6-12 volt DC power supply. Use a switch such as a knife
switch in the circuit to control the supply of electricity to the primary coil. Attach the secondary coil (larger
outer coil) to a galvanometer (sensitive electrometer). Insert the primary coil into the secondary coil (do not
insert the iron core for step 1 below.
1. With the electricity flowing to the primary coil and inserted into the secondary, place the iron core into
the center of the primary coil and note the meter deflection. Note the absence of meter deflection when
the soft iron core is at rest. Move the iron coil up and down into and out of the primary coil field.
Deflection of the galvanometer should be evident. Note the direction of the galvanometer needle, which
should vary depending upon if you are inserting or removing the core.
2. Repeat step one above, but move the primary coil (with iron core still inside) into and out of the
secondary coil. Note deflection.
3. Repeat step two above, but remove the iron core. Note the absence of deflection.
4. Reverse the polarity of the electricity flowing to the primary coil. Opposite galvanometer needle
movement will be observed.