Analysis of an L-R-C Series Circuit

[sully677]

Homework Statement

An L-R-C series circuit is constructed using a 175{ \Omega} resistor, a 12.5uF capacitor, and an 8.00 mH} inductor, all connected across an ac source having a variable frequency and a voltage amplitude of 25.0V

At the angular frequency in part A, find the potential difference across the ac source, the resistor, the capacitor, and the inductor at the instant that the current is equal to one-half its greatest positive value.

Homework Equations

V=IZ

The Attempt at a Solution

I found the voltage for all of them and divided by 2 since the current is half, but I can't get the right answer.

 

[Andrew Mason]

Homework Statement

An L-R-C series circuit is constructed using a 175{ \Omega} resistor, a 12.5uF capacitor, and an 8.00 mH} inductor, all connected across an ac source having a variable frequency and a voltage amplitude of 25.0V

At the angular frequency in part A, find the potential difference across the ac source, the resistor, the capacitor, and the inductor at the instant that the current is equal to one-half its greatest positive value.

Homework Equations

V=IZ

The Attempt at a Solution

I found the voltage for all of them and divided by 2 since the current is half, but I can't get the right answer.

You are incorrectly assuming that the voltage and current are in phase. You have to determine the phase angle between voltage and current.

AM

 

[sully677]

okay. so once the phase angle is solved for, where do you go?

 

[Andrew Mason]

okay. so once the phase angle is solved for, where do you go?

Use expressions for V and I as a function of time eg.:


$$I = I_0\sin{(\omega t)}$$

$$V = V_0\sin{(\omega t + \phi)}$$

What is the relationship between V₀ and I₀? What is the value for $\omega t$ when I = .5I₀?

AM