In physics, we measure quantities like length, mass, time, temperature, force, etc., using instruments.

But no matter how perfect our tools seem, every measurement has uncertainties and errors.

Now let’s explore these types of errors in that context:

1️⃣ Systematic Error 

🎯 Definition:

A systematic error is a consistent and repeatable error caused by some imperfection in the measurement system.

📌 Causes (in measurement techniques):

• Instrumental bias – like a faulty balance that always adds 2 g

• Zero error – a vernier caliper not starting at 0

• Environmental factors – e.g., expansion of metal scales in heat

• Personal habits – like always viewing a scale from an angle (parallax)

  
  

⚠️ Scientific Effect:

• Affects the accuracy (how close you are to the real value)

• Doesn’t go away by repeating the experiment

• Shifts all values in the same direction

  
  

🧪 Example in physics:

Using a stopwatch that is slow by 0.2 s always → all time readings are too small.

2️⃣ Random Error 

🎯 Definition:

A random error changes unpredictably from one measurement to another. It’s caused by tiny fluctuations in the measuring process.

📌 Causes (in measurement techniques):

• Reaction time of humans using a stopwatch

• Vibrations during weighing

• Slight electrical fluctuations in sensors

  
  

⚠️ Scientific Effect:

• Affects the precision (how consistent your readings are)

• Can be reduced by taking the average of repeated measurements

🧪 Example in physics:

Measuring a pendulum period and getting 1.92 s, 1.94 s, 1.91 s — due to tiny disturbances or timing reactions.

3️⃣ Absolute Error 

🎯 Definition:

The absolute error is the actual amount by which your measured value differs from the true value, expressed in the same unit.

Absolute Error=∣Measured Value−True Value∣

📌 In measurement techniques:

It gives the true gap between what you got and what you should’ve gotten.

🧪 Example in physics:

If the true length of a rod is 100.0 cm and you measured 98.7 cm:→ Absolute error = |98.7 – 100.0| = 1.3 cm

4️⃣ Relative Error 

🎯 Definition:

The relative error is the absolute error divided by the true value — a dimensionless ratio.

Relative Error=Absolute Error / True Value .

​

📌 In measurement techniques:

Helps understand whether an error is significant for the size of what you’re measuring.

🧪 Example in physics:

Absolute error = 1.3 cm, true length = 100.0 cm→ Relative error = 1.3 / 100.0 = 0.013 (or 1.3%)

5️⃣ Percentage Error

🎯 Definition:

The percentage error is just the relative error multiplied by 100, making it easy to interpret.

📌 In measurement techniques:

Gives a quick sense of measurement quality.A 0.5% error = excellent; a 20% error = poor.

🧪 Example in physics:

Relative error = 0.013→ Percentage error = 0.013 × 100 = 1.3%

🔬 In Real Measurement Techniques:

Vernier Caliper:

• Zero error (systematic) if the vernier scale doesn't align with zero

• Parallax error if your eye isn’t straight → causes random error

Stopwatch:

• Reaction time = random error

• Sticky buttons = systematic error

Balance:

• Uneven table = systematic error

• Airflow in room = random error

  
  

🧠 KEY TAKEAWAYS:

• Systematic Error → same every time (can be corrected)

• Random Error → changes every time (reduced by averaging)

• Absolute Error → raw difference

• Relative Error → scaled difference

• Percentage Error → easy-to-read performance %