Inductance:l/r time constants

l/r time constants

An l/r time constant is the time required for current through a conductor to increase to 63.2% or decrease to 36.8% of the maximum current. An RL circuit is shown in Figure 19-9. L/R is the symbol used

Figure 19-10 charts the growth and decay (or in- crease and decrease) of a magnetic field, in terms of time constants. It takes five time constants to fully transfer all the energy into the magnetic field, or to build up the maximum magnetic field. It takes five full-time constants to completely collapse the magnetic field.

Questions

1. What is a time constant for an inductor?

2. How is a time constant determined?

3. How many time constants are required to fully build up a magnetic field for an inductor?

4. How many time constants are required to fully collapse a magnetic field for an inductor?