Understanding Phase Shift in RC Circuits

[pat666]

Homework Statement

Pls see the attachment.

Homework Equations

The Attempt at a Solution

Obviously I have B and C correct but for a the only thing I can find is tan(phi)=X_L-X_c/R
This seems to be for a series RLC circuit though and I only have RC.
also I know that the current lags the p.d by 90⁰ in an RC circuit but I can't see how I can use this?
any help appreciated.

 

[rl.bhat]

Phase angle can found by using

cosφ = R/sqrt(R^2 + XC^2)

 

[pat666]

I don't know capacitive inductance though?

 

[rl.bhat]

I don't know capacitive inductance though?

Sorry. It should be XC. = 1/ωC

 

[pat666]

Thanks that worked, although the answer was negative 89 degrees?

 

[ehild]

You can use the equation tan(phi)=(XL-Xc)/R for a series RCL circuit, even for XL=0 as it is the case now.

ehild