What would the voltage across the resistor be at t = 0+?

Suppose an RL circuit with a time constant of 5ms was driven by a 5 volt source. What would the voltage across the resistor be at t = 0+?

Answer:
Well, I need to make some assumptions about the circuit before I can answer:
1. The R and L are in series.
2. The 5V source is a DC source
3a. The 5V source is connected at t=0, or
3b. the current at t=0 is zero.

So if these are correct, then the current at t=0+ is also zero, since the inductor will not let current jump instantly. You can think of current in an inductor as a flywheel, the bigger the inductance, the bigger the rotational mass. The speed of the flywheel will be a continuous function over time, like the current in an inductor.

If the current at t=0+ is zero, then by ohms law, the voltage on the resistor is also zero.
Initially the inductor looks like a break. That means no electrons are flowing across the resistor. That means the voltages are equal at five volts.

Is this homework?
In msec, I think 5e^(t/5)?

Does that look right?

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