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I 36 THE I -OY ELECTRICIAN

% ohm coil — 3 feet % inch
I ohm coil — 6 feet 1% inches
2 ohm r )il — 12 feet 2% inches
5 ohm coil — 30 feet 6% inches

10 ohm coil —— 61 feet

20 ohm coil —— 122 feet

3o'ohm coil — 183 feet

50 ohm coil — 305 feet

These lengths of wire are then wrapped on the spools in
the following manner.

This method of winding is known as the non-inductive
method, because the windings do not generate a magnetic

SPOOL

 

 

 

 

   

HERE

’ HEAVY COPPER
WIRE

FIG. n8. — Resistance-Coil. A shows how the Wire is doubled and wound on
the Spool. B is the completed Coil.

field, which might affect the galvanometer needle used in
connection with the Wheatstone bridge as described later

on.
Each length of wire should be doubled exactly in the

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