I need help with these problems for my final physics assignment of the semester
ID: 2302413 • Letter: I
Question
I need help with these problems for my final physics assignment of the semester so I can understand it for my final!
Please provide solutions,
At time t = 0, the switch in the circuit below is thrown to position P. Data: delta vs=25 V, R = 1.5 M ohm, L = 30 mH. (a) What is the time constant of the circuit after the switch is thrown to position PI (b) What is the maximum current that the power source can produce in this circuit? (c) What is the current in the circuit when t = 15 ns? (d) What is the polarity of the inductor at the time in part (c)? In the circuit of problem 3, (a) how many time constants does it take after the switch is thrown to position P for the current in the circuit to climb to Vz of its maximum value? (b) How many time constants does it take after t = 0 for the current to climb to within 10% of its maximum value?Explanation / Answer
3)
a)Time constant, T = L/R = 30*10^-3/1.5*10^6 = 20*10^-9 s = 20 ns
b) Imax = V/R = 25/1.5*10^6 = 16.67*10^-6 = 16.67 micro A
c) i = Imax*(1-e^(-t/T)
= 16.67*10^-6*(1 - e^(-15/20))
= 7.52 micro A
d) left +ve and right -ve
5)
c) i = Imax*(1-e^(-t/T)
0.5*Imax = Imax*(1 - e^(-15/20))
0.5 = 1 - e^(-t/T)
e^(-t/T) = 1-0.5
t = -T*ln(0.5)
= 0.693*T
b)
i = Imax*(1-e^(-t/T)
0.1*Imax = Imax*(1 - e^(-15/20))
0.1 = 1 - e^(-t/T)
e^(-t/T) = 1-0.1
t = -T*ln(0.9)
= 0.1054*T