For a coil with a resistance of 15 ohms, what is the formula used to calculate the time constant?

The time constant for a coil, which is a key concept in understanding the behavior of inductive circuits, is calculated using the formula TC = L/R. In this context, the time constant (TC) represents the time it takes for the current to reach approximately 63.2% of its maximum value after a voltage is applied, or to decay to about 36.8% after the voltage is removed.

Here, L denotes the inductance of the coil (measured in henries), and R represents the resistance (measured in ohms). This relationship demonstrates that the time constant is directly proportional to the inductance and inversely proportional to the resistance. A higher inductance means that it takes longer for the current to reach its steady state, while a higher resistance leads to a quicker response time.

Thus, when using the correct formula, understanding the relationship between inductance and resistance is crucial for predicting how quickly a coil responds to changes in voltage or current.