What is the formula to calculate the time constant of an RL circuit?

The formula to calculate the time constant (ฯ) of an RL circuit is:

ฯ = L / R

where:

ฯ is the time constant (in seconds),

L is the inductance of the coil (in henries, H), and

R is the resistance in the circuit (in ohms, ฮฉ).

In summary, the time constant of an RL circuit is equal to the inductance divided by the resistance. It gives an indication of how fast the current will change in the circuit due to the presence of the inductance and resistance. A larger time constant indicates slower changes in current, while a smaller time constant implies faster changes.