2330 Level 3 questions

[jas_singh]

Hi

I have 5 questions with answers with are:

1) A resistor of 28_ is connected to a inductor of 12mH and a capacitor of 24μF. Calculate

the impedance presented to the 50Hz supply.

XL = 2πfL = 3.77_, XC = 1 / (2πfC) = 132.63_, Z = √ (R2 + (XC- XL)2 = 131.87_

2) A resistor of 38_ is connected to a inductor of 124mH and a capacitor of 100μF.

Calculate the impedance presented to the 50Hz supply.

XL = 2πfL = 38.96_, XC = 1 / (2πfC) = 31.83_, Z = √ (R2 + (XL- XC)2 = 38.66_

3) A resistor of 12k_ is connected to a inductor of 56.92mH and a capacitor of 178μF.

Calculate the impedance presented to the 50Hz supply.

XL = 2πfL = 17.88_, XC = 1 / (2πfC) = 17.88_, In this case XL=XC, so Z=R = 12k_

4) A resistor of 164_ is connected to a inductor of 84mH and a capacitor of 18μF. Calculate

the impedance presented to the 50Hz supply.

XL = 2πfL = 26.39_, XC = 1 / (2πfC) = 176.84_, Z = √ (R2 + (XC- XL)2 = 222.56_

5) A resistor of 216_ is connected to a inductor of 136mH and a capacitor of 124μF.

XL = 2πfL = 42.73_, XC = 1 / (2πfC) = 25.67_, Z = √ (R2 + (XL- XC)2 = 216.67_

Does anyone know how to work them out as im having problems getting the correct answer.

thanks

 

[ADS]

Hi 1) A resistor of 28_ is connected to a inductor of 12mH and a capacitor of 24μF. Calculate

the impedance presented to the 50Hz supply.

XL = 2πfL = 3.77_, XC = 1 / (2πfC) = 132.63_, Z = √ (R2 + (XC- XL)2 = 131.87_

Is that not the correct answer?

 

[jas_singh]

yes thats the correct answer but not sure how they got it

do you know how to do the first and show working out??

 

[armbands0]

Reactance of inductor XL = 2 x 3.141 (pi) x 50 x .012 = 3.769R

Reactance of Capacitor XC = 1/2 x 3.141 x 50 x .000024 = 132.65R

Circuit reactance = XC - XL = 128.88R

Z = square root of (28 x 28 + 128.88 x 128.88) = sq root of 17394.05 = 131.88R

(Inductor has to be in Henry's for calculation and Capacitor has to be in Farads)

Any help?

 

[jas_singh]

thanks mate

that has helped alot

i can now to the other questions