Question

1. What is reactance and why is different from resistance?

2. What is a phasor diagram and how is it useful? (No Star Trek answers, please.)

Answer 1

1) Reactance : In electrical circuits recatance is nothing but opposition to free flow of current reaated by the circuit elements.

Resistance : It is opposition to the flow of current offered by Resistors.

• So, We know that basic circuit elements are Resistors , Capacitors and Inductors.
• Specifically resistance term is used for only resistors. Reactance is resistance offerd by capacitors and inductors.
• Resistance depends on Temperature but not on frequency of power source( voltage , current)
• But reactance depends on frequency of power source.
• Resistance R = V/I
• Reactance different types 1 ) Inductive reactance( resistance offered by inductor) X L = 2ΠfL f- frequency L- inductance
• 2) capacitive reactance( resistance offered by capacitor). Xc = 1/(2Πfc) c - capacitance
• So, in a circuit consists of Resistor and Capacitor and Inductor. So, resistance offerd by entire circuit is called as Impedance.
• Basically the reactance come into picture only if we use AC source because only AC source has frequency.

2) Phasor diagram is used to solve a circuit assuming R and XL and Xc on a xy plane as vectors.

Because in inductor current lags Π/2 (90°) with voltage

And in capacitor current is Π/2 ( 90°) forward the voltage .

But in resistors current is in phase with voltage.

So, in order to find impedence of entire circuit and also if we are given impedence and two of the R or C or L

And f are given we can easily find other.

Please rate it if u like