Time constant symbol in physics

TAU

This Greek letter represents the interval for a system to decay to about 37% of its initial value, often seen in exponential processes like RC circuits.

In physics, the time constant is a value that describes how quickly a system responds to changes, like a capacitor charging or discharging. The standard symbol for this time constant is the Greek letter tau, written as "T" with a loop (τ), which is often spelled out as "TAU" in crosswords. The clue is straightforward—no wordplay—just a direct reference to a common physics notation.