00:01
Hello, so we have our given data here where our voltage source is equal to 92 volts.
00:08
Our resistance is equal to 1 .2 kilooms, which is equal to 1 ,200 oms.
00:15
And then we have our inductance, which is going to be 28h.
00:20
Now, the first thing we need to find is the rl circuit growth equation, which we can use i of t as equal to i max.
00:31
1 minus e to negative t over our time constraint.
00:38
Now, we need to know what our time constraint is.
00:41
So our time constraint is going to be l over r, our inductance over our resistance.
00:49
And we actually have this, so solving for t when i of t is equal to 0 .72 i max.
01:05
We get that 0 .72 is equal to 1 minus e negative t over our time constraint.
01:12
Now we rearrange to solve for our time constraint is equal to 1 minus 0 .72, which is equal to 0 .28.
01:23
And so we get that t is equal to negative time constraint, natural log of 0 .28.
01:36
So you can plug this into the calculator...