Omggg Determining voltage between point a and b given R = 40 ohms

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riseofphoenix
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Omggg :( Determining voltage between point a and b given R = 40 ohms

PHYSICSHELP_zpse6fd0131.png


This is what I did for part A:1) ΔVrms = Vmax(1/√2)
ΔVrms = (145)(0.707)
ΔVrms= 102.53

2) Ztotal = √[R² + (XL - XC)²]

XL = 2πfL
XL = 2π(40)(185 x 10^-3)
XL = 46.49

XC = 1/2πfC
XC = 1/[2π(40)(65 x 10^-6)
XC = 1/0.016336382
XC = 61.21

Ztotal = √[40² + (46.49 - 61.2)²]
Ztotal = √(1600 + 216.67)
Ztotal= √(1816.67)
Ztotal = 42.62

3) ΔVrms = (Irms)(Zab)
ΔVrms = (ΔVrms/Ztotal)(Zab)
ΔVrms = (102.53/42.62)(40)
ΔVrms = (2.405)(40)
ΔVrms = 96.2 V

:o
 
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For your Ztotal, why do you subtract the reactance component from the real (resistance) component when you summed them in quadrature (square root of sum of squares)?
 
gneill said:
For your Ztotal, why do you subtract the reactance component from the real (resistance) component when you summed them in quadrature (square root of sum of squares)?

Oh oops, that's supposed to be a plus...

But I still get the wrong answer :(

I think I may have a mental breakdown...
 
riseofphoenix said:
Oh oops, that's supposed to be a plus...

But I still get the wrong answer :(

I think I may have a mental breakdown...

What value did you calculate?
 
gneill said:
What value did you calculate?

The answer is 96.2 :D
Thanks for catching that!
I think I've been studying for too long