Question

What is the relationship between current (I) and voltage (E) in a circuit consisting of a capacitor in series with a resistor?
1. I and E are in phase across the capacitor
2. I leads E across the resistor
3. E leads I across the capacitor
4. I and E are in phase across the resistor

Answer 1

Correct Answer - Option 4 : I and E are in phase across the resistor

• In a pure resistive circuit, the current is in phase with the voltage. Hence the power factor is unity
• In a pure capacitive circuit, current leads the voltage by 90°. Hence the power factor is zero leading
• In a circuit consists of a resistor and a capacitor, the current lead the voltage by an angle less than 90° and it is leading.
• Since V = IR across the resistor, and the imaginary part of resistance is zero across a resistor, the voltage and the current will be in phase across the resistor.