Capacitive Reactance Quiz with Answer Key

📚 Quick Study Guide

• ⚡ Capacitive Reactance: Opposition to alternating current (AC) in a capacitor.
• 📐 Formula: $X_C = \frac{1}{2\pi fC}$, where:
  • $X_C$ is capacitive reactance (in ohms)
  • $f$ is the frequency (in hertz)
  • $C$ is the capacitance (in farads)
• 📈 Frequency Relationship: Capacitive reactance is inversely proportional to frequency. Higher frequency means lower reactance.
• 📉 Capacitance Relationship: Capacitive reactance is inversely proportional to capacitance. Higher capacitance means lower reactance.
• 💡 DC Circuits: Capacitors block direct current (DC) after they are fully charged; hence, capacitive reactance is considered infinite in DC circuits.
• 📝 Units: Reactance is measured in ohms (Ω), just like resistance.

🧪 Practice Quiz

1. What is capacitive reactance?
   1. A) The opposition to current flow in an inductor.
   2. B) The opposition to current flow in a resistor.
   3. C) The opposition to alternating current flow in a capacitor.
   4. D) The opposition to direct current flow in a capacitor.
2. What formula is used to calculate capacitive reactance?
   1. A) $X_C = 2\pi fC$
   2. B) $X_C = \frac{1}{2\pi fC}$
   3. C) $X_L = 2\pi fL$
   4. D) $X_L = \frac{1}{2\pi fL}$
3. If the frequency of the AC source increases, what happens to the capacitive reactance?
   1. A) Increases
   2. B) Decreases
   3. C) Stays the same
   4. D) Becomes infinite
4. If the capacitance of a capacitor increases, what happens to the capacitive reactance?
   1. A) Increases
   2. B) Decreases
   3. C) Stays the same
   4. D) Becomes infinite
5. What is the capacitive reactance in a DC circuit after the capacitor is fully charged?
   1. A) Zero
   2. B) Infinite
   3. C) Equal to the resistance
   4. D) Equal to the capacitance
6. Capacitive reactance is measured in what unit?
   1. A) Farads
   2. B) Henrys
   3. C) Ohms
   4. D) Amperes
7. A capacitor has a capacitance of 10 μF and is connected to a 50 Hz AC source. What is the capacitive reactance?
   1. A) 318.31 Ω
   2. B) 31.83 Ω
   3. C) 3.18 Ω
   4. D) 0.32 Ω