- #1

znaya

- 18

- 0

## Homework Statement

Consider, in the circuit from the image,

i1(t) = 5 cos(2t + 10º)

v1(t) = 10 cos(2t - 60º).

Find the value of the current ix(t).

Options given:

A: ix(t) = 9.9 cos(2t - 129.2º)

B: ix(t) = 9 cos(2t - 29.2º)

C: ix(t) = 99 cos(2t + 129.2º)

D: ix(t) = 0.99 cos(2t + 130º)

## Homework Equations

Ohm's law.

V=IR

## The Attempt at a Solution

My approach was, first calculate the amount of current produced by the voltage source, combining the R + C + L in series and ignoring the current source, the result was 2<-59º(or 1.03 -1.7j)

After I calculated the amount of current from the current source. I ignored the voltage source (short circuiting the circuit) and calculated L || (C + R) and the amount of current going to (C + R) is 11.86<-25.3º (or 10.7 -5.06j).

Finally i summed the currents:

1.03-1.7j + -(10.7-5.06j) ====> negative because it goes in the opposite direction from the one in the image.

The result was -9.67+3.36j or 99.7<-19.16º [+180º];

That is 99.7 < 160.84º or

**99.7 cos(2t + 160.84º)**

That is near option C but not exactly! What am I doing wrong?

Thanks for any help.