1) expand and simplify:
(x-1/x)2
2) factorise:
x^2+6x+8
3) transpose to make t the subject:
v=200e^(-Rt/L)
The voltage drop, v volts, across and inductor L henrys at time t seconds is given by: v=200e^(-Rt/L)
R=150 ohms
L=12.5*10^-3 H
What time does it take for the voltage to reach 85 volts>
could you go through it step by step if possible and also for the (x-1/x)^2 question.
Thanks BabyMilo for the quick reply.
$\displaystyle v = 200e^{\frac{-Rt}{L}}$
$\displaystyle \frac{v}{e^{\frac{-Rt}{L}}} = 200$
$\displaystyle e^{\frac{-Rt}{L}} = \frac{v}{200}$
$\displaystyle \frac{-Rt}{L} = ln(\frac{v}{200})$
$\displaystyle -Rt = ln(\frac{v}{200})*L$
$\displaystyle t = \frac{ln(\frac{v}{200})*L}{-R}$
sub in the numbers.
$\displaystyle t = \frac{ln(\frac{85}{200})*12.5*10^{-3}}{-150}$
t = 71.31×10^−6s