Transient Response of Electrical Network

[jaus tail]

Homework Statement

Homework Equations

In Capacitance current leads voltage
In Inductance current lags voltage
For oscillations R = 0

3. The Attempt at a Solution
Since current is leading voltage in above question, impedance is capacitive.
Book answer is D for both.
How?

And for 3rd question, should R be 0, else circuit is damped. Oscillations mean undamped system so R = 0.

 

[BvU]

And for 3rd question, should R be 0, else circuit is damped

No. Transient (damped) oscillations are also oscillations.

 

[BvU]

Two for the price of one ? What is the complex impedance $Z$ in exercise 2 ?

 

[jaus tail]

z = v / i = 200 sin (2000t +50) / 4 cos (2000t + 11.32)
= 50 sin (2000t + 50) / sin (2000t + 11.32 + 90) = 50 sin (2000t + 50) / sin (2000t + 101.32)
For this to be resistance the phase angle must be zero which doesn't happen. So I think D cannot be right answer. Resistance cannot vary with time so the sine term must be a constant and not a time variant.

 

[BvU]

I agree there must be something wrong with the book answer for exercise 2.