Ohm, True. The true ohm is the resistance of a column of mercury 106.24 centimetres long and one square millimetre in cross-sectional area. An ohm may be measured by a No. 30 copper wire nine feet and nine inches long. If larger size wire is used the piece must be proportionately longer, since the resistance is less.
Ohmic Resistance. True resistance as distinguished from spurious resistance, or counter electro-motive force. (See also [Resistance, Ohmic].)
Ohm’s Law. The basic law which expresses the relations between current, electro-motive force, and resistance in active circuits. It is formulated as follows:
1. The current strength is equal to the electro-motive force divided by the resistance.
2. The electro-motive force is equal to the current strength multiplied by the resistance.
3. The resistance is equal to the electro-motive force divided by the current strength.
O. K. A telegraphic signal meaning yes, or all right. It is supposed to be a misspelled form of all correct, “Oll Kerrekt.”
Okonite. A form of insulation for wires and conductors; a trade name applied to insulations, and protected by copyright.
Open Arc. A voltaic arc not enclosed.
Open Circuit. (See [Circuit, Open].)