How to find least count of any measuring apparatus.
💡 What is Least Count?
Least Count (L.C.) is the smallest measurement that an instrument can read accurately.
It tells you the precision of the instrument — basically, how fine a measurement it can take.
🧠 Think of it as:
"How small can this device measure?"
🔍 How to Find Least Count of Any Apparatus?
There’s a universal formula:
Least Count = Value of One Main Scale Division / Number of Divisions on the Vernier or Dial Scale
But depending on the instrument, the method varies. Here's how you do it for common tools:
1. Ruler / Scale (Meter Scale)
Each division = 1 mm = 0.1 cm
➡️ L.C. = 0.1 cm
2. Vernier Caliper
✅ Formula:
L.C. = 1 MSD - 1 VSD
(Or simply: L.C. = Smallest reading on main scale / number of vernier divisions)
📌 Example:
- 1 cm = 10 divisions → 1 MSD = 1 mm
- Vernier has 10 divisions = 9 mm
➡️ L.C. = 1 mm – 0.9 mm = 0.1 mm
3. Screw Gauge / Micrometer
✅ Formula:
L.C. = Pitch / Number of divisions on circular scale
📌 Example:
- Pitch = 1 mm (one full rotation moves the spindle 1 mm)
- Circular scale = 100 divisions
➡️ L.C. = 1 mm / 100 = 0.01 mm
4. Stopwatch / Analog Timer
Check the smallest time interval it shows — usually:
➡️ 0.1 sec or 0.01 sec
⚠️ Note:
The smaller the least count, the more precise the instrument is. But don’t confuse accuracy with precision — that's another beast.
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