time constant

noun Electricity.

1. the time required for a changing quantity in a circuit, as voltage or current, to rise or fall approximately 0.632 of the difference between its old and new value after an impulse has been applied that induces such a change: equal in seconds to the inductance of the circuit in henries divided by its resistance in ohms.

noun

1. electronics the time required for the current or voltage in a circuit to rise or fall exponentially through approximately 63 per cent of its amplitude