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WAEC Physics 2018 Paper

Question : 44

Total: 50

\Omega

X_{c}

\Omega

X_{L}

\Omega

. The impedance of the circuit is

Solution:

Concept:

For a series R-L-C circuit, the total opposition to current is the impedance, which combines resistance and the net reactance.

Explanation:

The impedance formula is

Z = \sqrt{R^2 + (X_L - X_C)^2}

Given:

R = 10\ \Omega

X_L = 9\ \Omega

X_C = 4\ \Omega

First, find the net reactance:

X_L - X_C = 9 - 4 = 5\ \Omega

Substitute into the formula:

Z = \sqrt{10^2 + 5^2}

Calculate:

Z = \sqrt{100 + 25} = \sqrt{125}

\sqrt{125} = 11.18\ \Omega \approx 11.2\ \Omega

Answer:

Therefore, the impedance of the circuit is

11.2\ \Omega

. The correct option is D.

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