Key relationship
XL=ωL; XC=1/(ωC); Z=√(R²+(XL−XC)²); tanφ=(XL−XC)/R.
Physics · Class 12
Reactance, impedance and phasors
Inductor reactance grows with frequency; capacitor reactance falls. Their signed difference determines phase, and the resistor sets the in-phase component.
Open the interactive experiment →Reactance, impedance and phasors
சுருள் மறுமின்தடை அதிர்வெண்ணுடன் உயரும். தேக்கி மறுமின்தடை அதிர்வெண்ணுடன் குறையும்.
Key notes, relationships and model limits
Remember
Inductor reactance grows with frequency; capacitor reactance falls. Their signed difference determines phase, and the resistor sets the in-phase component.
Common trap
Reactances combine with their phase signs; do not add R, XL and XC as ordinary positive magnitudes.
Model limits
Ideal lumped series LCR, steady sinusoid, constant R/L/C.
What you will learn
Use the controls and plotted relation to explain reactance, impedance and phasors.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
At R=50 Ω, L=0.1 H, C=100 µF and 50 Hz, XL≈31.42 Ω and XC≈31.83 Ω.
Why this matters
The model connects reactance, impedance and phasors with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
At XL=XC, the impedance of series LCR equals?
- XL+XC.
- R, with zero phase difference.
- Zero even when resistance is positive.
Read the explanation
R, with zero phase difference.
Course connection: Class XII Chapter 7. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.