An alternating voltage source is connected to a resistor and a capacitor. Which of the following statements about phase angle between voltage and current is correct?
Correct answer: C. In the resistor, I and V are in phase - In the capacitor, I leads V by 90°
- A. In the resistor, I leads V by 90°-In the capacitor, I leads V by 90°
- B. In the resistor, I lags V by 90° - In the capacitor, I leads V by 90°
- C. In the resistor, I and V are in phase - In the capacitor, I leads V by 90°
- D. In the resistor, I and V are in phase - In the capacitor, I lags V by 90°
Explanation
In a resistor, voltage and current stay in phase. In a capacitor, current leads voltage by 90° because the capacitor must charge before voltage builds up.
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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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