lauraj
Senior Member
- Location
- Portland, Oregon
I was teaching a lesson the other day on inductors, using a transformer as an example. I talked about how a high current flows for a short time until the field is built up. I've always thought that this is due to the absence of cemf, but as the field builds up, the current drops. Is this correct?
A little bit later, we were looking at the time constant for inductors, t=L/R and how inductors resist a change in current.
Then a question comes up - if inductors oppose a change in current, why do we have that initial high current in transformers?
I believe the time constant would still be there, but because we have bigger R and smaller L at this point, it is so fast that we do not notice. Is this correct?
A little bit later, we were looking at the time constant for inductors, t=L/R and how inductors resist a change in current.
Then a question comes up - if inductors oppose a change in current, why do we have that initial high current in transformers?
I believe the time constant would still be there, but because we have bigger R and smaller L at this point, it is so fast that we do not notice. Is this correct?