- #1
yosimba2000
- 206
- 9
I just found out V = Acos(wt+phi) is made up of both radians and degrees, where w is rad/s and phi is degree.
You have to convert either one to the other to calculate it.
Assume phi is 0 degrees. I(t) = Icos(wt), and w is radian/s.
So then capacitor impedance is -j/wC.
V(t) = (I<0) * (1/wC<-90)
V(t) = 1/(wC) < -90 <-- change 90 degree to pi/2 radian
V(tr) = I/wC*cos(wt-pi/2) <--- this is solved using radians!
Ok, then assume we change from radians to degrees. So I(t) = Icos(57.3wt). We use 57.3 since there are about 57.3 degrees per radian.
Capacitor impedance then becomes -j/(57.3wC).
V(t) = (I<0) * (1/(57.3wC)) < -90
V(t) = I/(57.3wC)<-90
V(td) = I/(57.3wC)*cos(57.3wt-90) <----this is solved using degrees!
The resulting V(t) values do not match!
Assume all values are 1.
So V(tr) = 1/(1*1)cos(1-pi/2) using radians, comes out to be 0.84147.
And V(td) = 1/(57.3)*cos(57.3-90) using degrees, comes out to be 0.0146.
How come they don't match? They should be equivalent.
You have to convert either one to the other to calculate it.
Assume phi is 0 degrees. I(t) = Icos(wt), and w is radian/s.
So then capacitor impedance is -j/wC.
V(t) = (I<0) * (1/wC<-90)
V(t) = 1/(wC) < -90 <-- change 90 degree to pi/2 radian
V(tr) = I/wC*cos(wt-pi/2) <--- this is solved using radians!
Ok, then assume we change from radians to degrees. So I(t) = Icos(57.3wt). We use 57.3 since there are about 57.3 degrees per radian.
Capacitor impedance then becomes -j/(57.3wC).
V(t) = (I<0) * (1/(57.3wC)) < -90
V(t) = I/(57.3wC)<-90
V(td) = I/(57.3wC)*cos(57.3wt-90) <----this is solved using degrees!
The resulting V(t) values do not match!
Assume all values are 1.
So V(tr) = 1/(1*1)cos(1-pi/2) using radians, comes out to be 0.84147.
And V(td) = 1/(57.3)*cos(57.3-90) using degrees, comes out to be 0.0146.
How come they don't match? They should be equivalent.