In normal metals the collision time is typically  s, so for frequencies < 100 GHz  is very small and can be ignored; then this equation reduces to the DC conductance . Kinetic inductance is therefore only significant at optical frequencies, and in superconductors whose .
In normal metals, the collision time is usually around s, making it very small for frequencies below 100 GHz; thus, this equation simplifies to DC conductance. Kinetic inductance becomes significant only at optical frequencies and in superconductors where .