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Shinee
Shinee asked in Science & MathematicsEngineering · 8 years ago

Circuits 2 help ,kindly help me?

im almost 1 hour here solving for this sinusodal problem , i really cant solve it, please help me, dont worry this is not an assignment , i need this for my exam next week ,and i need to understand it.

here it is. im sorry i upload it flickr for privacy

heres the problem

http://www.flickr.com/photos/91102274@N08/83603899...

Update:

so whats the final answer for both?

2 Answers

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  • billrussell42
    Lv 7
    8 years ago
    Favorite Answer

    Assuming "maximum amplitude" means peak current of 20 amps...

    Period is 1 ms, so frequency is 1 over that or 1 kHz.

    ω = 2πf = 6.28 rad/s

    at t = 0, I = 10

    I = 20 cos (ωt + φ) = 20 cos (6.28t + φ)

    10 = 20 cos (φ)

    φ = arccos 0.5 = 60º

    I = 20 cos (6.28t + 60º)

  • Colin
    Lv 7
    8 years ago

    One cycle in 1ms; 1000 cycles per second.

    w =2*pi*1000 radians per second.

    i(t) = Imax*(cos w*t + arccos(i(0)/Imax))

    = 20*(cos 2*pi*100*t + arccos(10/20))

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