Question

Difficulty: EasyAlternating Current (AC) Circuits

An AC series circuit consists of a resistor of resistance R=6 ΩR = 6\ \Omega connected in series with an inductor of inductive reactance XL=8 ΩX_L = 8\ \Omega. What is the total impedance of the circuit?

  1. 10 Ω10\ \OmegaAnswer
  2. B
    14 Ω14\ \Omega
  3. C
    2 Ω2\ \Omega
  4. D
    100 Ω100\ \Omega

Answer

The total impedance of the circuit is 10 Ω10\ \Omega.
The net impedance ZZ in an AC series circuit containing a resistor and an inductor is given by Z=R2+XL2Z = \sqrt{R^2 + X_L^2}. Substituting R=6 ΩR = 6\ \Omega and XL=8 ΩX_L = 8\ \Omega yields Z=62+82=36+64=100=10 ΩZ = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100} = 10\ \Omega.

Step-by-Step Solution

1
Identify the formula for impedance in an RL series circuit
Z=R2+XL2Z = \sqrt{R^2 + X_L^2}
In an AC circuit, resistance and inductive reactance add vectorially at a 9090^\circ phase angle.
2
Substitute the given values R=6 ΩR = 6\ \Omega and XL=8 ΩX_L = 8\ \Omega into the formula
Z=62+82=36+64=100Z = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100}
Squaring each component gives the terms required under the radical.
3
Calculate the square root
Z=10 ΩZ = 10\ \Omega
The square root of 100 gives the net opposition to current flow (impedance).

Key Concept

Impedance of an RL Series AC Circuit
Estimated Time:45s
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