Physics Demo Number: 052

Approximate Run Time: 10 min

Dissectible Transformer

Demo Description

Show the components of a transformer by separating the primary coil from the iron core and the secondary coil. Demonstrate the advertised step down mode of the transformer.

Then use a Variac to run transformer as a step up transformer.

Scientific Principles

• Transformer action

• Electromagnetic Induction

Equipment

• Laminated-iron transformer core

• 3 Secondary Coils

• Variac

1

Equipment Location

• Kit (052) on [B-1-5] contains the components.

2

3

Instructions

Photo 1 shows the OEM information detail and two of the three secondary coils.

Photo2 shows the third secondary coil [mounted on half of the laminated-iron transformer core].

This third secondary coil is ready to be rotated 90 degrees about a horizontal axis and locked in place by the two pivoting Aluminum U-Bracket-Iron-core keepers.

Photo 3 shows the AC input cord plugged into the left side of the transformer base.

One may of course use the overhead projector modified digital multimeter from Kit(051) to let the class see that the output voltages are as advertised.

To demonstrate the reversibility of this process proceed as follows.

With the wall outlet end of the transformer AC input cord unplugged , one may carefully hook the variac to a secondary coil.

One may the turn the variac up to actually supply the advertised secondary coil voltage to the secondary coil.

Then careful attachment of the digital multimeter leads to the wall outlet end of the unplugged AC input cord of the transformer will verify that the nominal wall voltage of 120 VAC is now appearing across the bare plugs.

Writeup created by David A. Burba

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