MHT CET · Physics · Alternating Current

In an a.c. circuit containing \(L, C, R\) in series the ratio of true power to apparent power is
( \(\mathrm{Z}=\) impedance of the circuit and R is the resistance)

A \(\frac{\mathrm{Z}}{\mathrm{R}}\)
B \(\tan \phi\)
C \(\cot \phi\)
D \(\frac{\mathrm{R}}{\mathrm{Z}}\)

Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{\mathrm{R}}{\mathrm{Z}}\)

Step-by-step Solution

Detailed explanation

\(\text{Ratio} = \frac{\text{True Power}}{\text{Apparent Power}} = \cos \phi = \frac{\mathrm{R}}{\mathrm{Z}}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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In an a.c. circuit containing \(L, C, R\) in series the ratio of true power to apparent power is( \(\mathrm{Z}=\) impedance of the circuit and R is the resistance)

Step-by-step Solution

In an a.c. circuit containing \(L, C, R\) in series the ratio of true power to apparent power is
( \(\mathrm{Z}=\) impedance of the circuit and R is the resistance)