The r.m.s value of an alternating current is equal to its instantaneous value at an angle of
Correct answer: B. 45°
- A. 60°
- B. 45°
- C. 30°
- D. 90°
Explanation
The RMS value is I (rms) = I (peak) / √2. The instantaneous current is I (inst) = I (peak) sin(θ). Setting them equal gives I (peak) / √2 = I (peak) sin(θ), which simplifies to sin(θ) = 1/√2. This occurs at an angle of 45°
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About Alternating Current
Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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