Electronics and Communication Engineering - Automatic Control Systems - Discussion

Discussion Forum : Automatic Control Systems - Section 1 (Q.No. 21)
In the given figure the input frequency is such that R << Xc, then
v0 lags vi by 90°
v0 leads vi by 90°
v0 and vi are in phase
either (b) or (c)
Answer: Option

Voltage across capacitor lags by 90°.

4 comments Page 1 of 1.

Santosh Gupta said:   2 years ago
Here, we have to use phase angle formula.

Yes, you are right @Khatendra

It's 90°.

Arfeen said:   5 years ago
Yeah, @Kuldeep.

I agree with you answer should be C.

Kuldeep said:   6 years ago
i = vi/(r-jxc)
vo = i * (-jxc)
vo = vi * -jxc/(r-jxc)
r<< xc
vo = vi * -jxc/-jxc
vo = vi.

They should be in phase.

Khetendra Vashishtha said:   7 years ago
R << Xc. It means we neglect the R.

Tan-1 (Xc/R) = tan-1 (Xc/0) = 90.

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