00:01
Our general expression for the current in coil 1, i1 with respect to time, is equal to i max, the maximum current through coil 1, and e to the minus alpha t, and sine omega -t.
00:15
And for the expression given, we can read off the values.
00:19
Firstly, imax as 5 ampiers, alpha is read off to be 0 .025 per second.
00:33
And the angular frequency omega is read off to be 377 radiance per second.
00:44
So we can first find the i -1, dt, the rate of which this current in the coil is changing in coil 1, and this will help us find the mutual inductance.
00:58
So if we differentiate this expression with respect to t, we get that this is imaxe to the minus alpha -t.
01:10
T into minus alpha sine omega t plus omega -t cos omega -t.
01:24
So if we substitute our values at time t is equal to 0 .8 seconds, we get the i1 d t is equal to 5 ampiers, we'll suppress the units for now, and e to the minus alpha times t, both the values are known, so we get 0 .02, all into minus 0 .025 times sign of 0 .8 times omega which is 377 plus omega 377 times the cost, the time which is 0 .8, multiplied by omega 377.
02:30
And the cost, the time, which is 0 .78, multiplied by omega 377...