Induction Coil Demonstration Experiment


Accession Number:


A coil of fine insulated wire is wrapped around a vertically-mounted cylinder of cardboard. This cylinder is held upright by two brass rods and a bakelite (or similar) plate across its top. The cylinder is hollow. Fitted through a hole in the bakelite plate is a metal tube containing what appears to be thin wire or strips of graphite, packed lengthways inside the tube so just their ends are visible. This inner tube is removable, and is open at both ends.

This assembly is affixed to a varnished wooden base with beveled edges. On the base there are four electrical terminals. Two of these are connected to the exterior coil; these are labelled by a strip of paper taped to the wooden surface: PRIMARY. The other two terminals are labelled in the same way as SECONDARY. One of these is connected via a wire that passes underneath the other cylindrical tube; the other is connected to one of the “primary” terminals.

Underneath the base, holes are screwed that enable the various components to be screwed in place. Handwritten pencil markings at each end of the underside indicate the terminals as PRIMARY and SECONDARY, as on the top.

Alternative Name:

Primary Materials:

Wood, Metal: Copper Alloy, Metal: Iron Alloy


Typed on pieces of paper taped to the top of the base: “PRIMARY” “SECONDARY”

Handwritten in pencil on the bottom of the wooden base: “PRIMARY” “SECONDARY”

Dimensions (cm):

Height = 12cm, length = 20.5cm, width = 13.5cm


This is likely a student induction experiment, intending to demonstrate how a pulsed current in an outer coil can induce a current in the inner coil (or vice-versa).


Excellent: The metal components of the instrument are in very good condition, with very little sign of oxidation. The cardboard or wooden tube is covered in a plasticky coating; this is chipped and broken in places, and quite fragile. The wooden base has a few chips, but is in otherwise very good condition. There is one small hole in the base that does not have a corresponding component, possibly indicating the base was reused, a piece is missing, or a modification was made.

Associated Instruments:

Manufacturer: Unknown (Locally Made?)

Date of Manufacture: Late 19th or Early 20th Century


University of Toronto Department of Physics.

Historical Notes: