Key relationship
Without breakdown Vo=Vin RL/(Rs+RL); clamp Vo=Vz only when series current can supply load plus Iz≥0.
Physics · Class 12
Zener load regulation
The series resistor limits available current. A light load allows excess current through the Zener and clamps output. A heavy load can consume all available current, making the output fall below breakdown.
Open the interactive experiment →Zener load regulation
தொடர் மின்தடை கிடைக்கும் மின்னோட்டத்தை வரம்பிடும். அதிகச் சுமையில் ஜீனர் ஒழுங்குமுறை நீங்கலாம்.
Key notes, relationships and model limits
Remember
The series resistor limits available current. A light load allows excess current through the Zener and clamps output. A heavy load can consume all available current, making the output fall below breakdown.
Common trap
A Zener cannot hold its nominal voltage with arbitrarily heavy load or low supply.
Model limits
Ideal abrupt reverse clamp and resistive load; ignores minimum holding current, dynamic resistance and power limits. Series resistor always included.
What you will learn
Check current feasibility before assigning a regulated voltage.
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
12 V,Rs500 Ω,RL2000 Ω,Vz6 V gives IL3 mA,IS12 mA,IZ9 mA.
Why this matters
The model connects zener load regulation with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
A Zener can maintain Vz only if its current is?
- Necessarily negative
- Nonnegative in the clamp model
- Larger than all possible supply current
Read the explanation
The series current must cover load demand before any Zener current remains.
Course connection: Class XII Chapter 14. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.