Ans. A coil has an inductance of one henry when the product of the number of lines enclosed by the coil multiplied by the number of turns in the coil, when a current of one ampere is flowing in the coil, is equal to 100,000,000 or 108.
An inductance of one henry exists in a circuit when a current changing at the rate of one ampere per second induces a pressure of one volt in the circuit.
Ques. What is the henry called?
Ans. The coefficient of self-induction.
Fig. 1,267.—Diagram illustrating the henry. By definition: A circuit has an inductance of one henry when a rate of change of current of one ampere per second induces a pressure of one volt. In the diagram it is assumed that the internal resistance of the cell and resistance of the connecting wires are zero.
The henry is the coefficient by which the time rate of change of the current in the circuit must be multiplied, in order to give the pressure of self-induction in the circuit.
The formula for the henry is as follows:
| magnetic flux × turns | ||
| henrys | = | |
| current × 100,000,000 |