ICSE Class 9 Physics: Measurements and Experimentations - Chapter 1

Jun 12, 2024

ICSE Class 9 Physics: Measurements and Experimentations - Chapter 1

Instructor: Anjana from LearnoHub

Key Topics Covered:

  1. Measurement of Length

    • Recap of fundamental quantities and SI units.
    • Measurement using non-standard instruments (pen, pencil) compared to standard instruments (meter scale, measuring tape).
    • Standard units for length: kilometers, meters, centimeters, millimeters.

  2. Using Standard Measuring Instruments

    • Meter Scale:
      • Commonly 1 meter (100 cm) and 30 cm scales.
      • Each cm divided into 10 mm (0.1 cm).
      • Example: Measuring a pencil.
    • Challenges in measuring lengths between scale divisions.

  3. Least Count Concept

    • Definition: Smallest value that can be measured using a measuring instrument.
    • Calculation:
      • Example for a scale: 1 cm / 10 divisions = 0.1 cm (or 1 mm).
      • Example for stopwatch: 5 seconds / 10 divisions = 0.5 seconds.
      • Example for ammeter: 1 amp / 10 divisions = 0.1 amp.

  4. Accuracy of Measurements

    • Accuracy increases with more decimal points.
    • Example: Measuring thickness with various tools.

  5. Various Measuring Instruments

    • Vernier Calipers:

      • Structure: Main scale, Vernier scale.
      • Calculating least count:
        • Main Scale Division (MSD), Vernier Scale Division (VSD).
        • Least count = MSD - VSD.
      • Use: More accurate measurements, up to 0.01 cm.
      • Example: Measuring the length of a root.
      • Zero Error: Positive and Negative zero errors, and their corrections.

    • Screw Gauge:

      • Structure: U-shaped frame, main scale, circular scale, spindle, stud.
      • Principle: Movement of screw threads.
      • Pitch: Distance moved in one rotation.
      • Least Count: Pitch / Number of divisions on circular scale.
      • Zero Error: Positive and Negative zero errors, and their corrections.
      • Example: Measuring thickness of a cardboard.

  6. Exercises and Examples

    • Stopwatch: Least count calculation (5 sec / 10 divisions = 0.5 sec).
    • Vernier Calipers: Correcting observed readings for zero error.
    • Screw Gauge: Finding least count (pitch / number of divisions).
    • Application to problems from Exercise 1B.