Answer: 4.33 A.
- A 2.50 A
- B 3.54 A
- C 4.33 A
- D 5.00 A
Correct answer: C. 4.33 A
Explanation: At t = 1/600 s, the phase is 100π/600 + π/6 = π/3. Therefore i = 5 sin(π/3) = 5×√3/2 = 4.33 A.
In a pure inductor the current lags the voltage by 90° (energy is briefly stored in the magnetic field before current responds); in a pure capacitor the current leads the voltage by 90° (current must flow to build up charge before voltage rises) - the mnemonic "ELI the ICE man" keeps these straight.
Concept context
AC circuits, impedance, LCR series circuit, resonance, transformers, and power factor.