EETC Circuit Theory 2

Question 1

In a series RLC circuit at resonance, what is the relationship between inductive reactance (XL) and capacitive reactance (XC)?

Accepted Answer

XL = XC

Answer

At resonance in a series RLC circuit, XL equals XC, causing them to cancel out and leaving only the resistance.

Question 2

A capacitor of 100 µF is connected to a 120V, 60Hz AC source. What is its capacitive reactance?

Accepted Answer

26.5 Ω

Answer

XC = 1/(2πfC) = 1/(2π × 60 × 0.0001) ≈ 26.5 Ω.

Question 3

Which theorem states that any two-terminal linear network can be replaced by a single voltage source in series with an impedance?

Accepted Answer

Thevenin's Theorem

Answer

Thevenin's Theorem replaces a complex linear network with an equivalent voltage source (Vth) in series with an equivalent impedance (Zth).

Question 4

Two resistors of 6 Ω and 12 Ω are connected in parallel. What is their combined equivalent resistance?

Accepted Answer

4 Ω

Answer

For parallel resistors: 1/Req = 1/6 + 1/12 = 3/12, so Req = 4 Ω.

Question 5

The time constant of an RL circuit is defined as the time for the current to reach what percentage of its final steady-state value?

Accepted Answer

63.2%

Answer

One time constant (τ = L/R) is the time for current to reach approximately 63.2% of its final steady-state value.

(EETC) Electrical Technician Certification Practice Test