Question

Instrumental error can occur due to _______
1. imperfect design
2. imperfect calibration of the measuring instrument
3. Both 1 and 2
4. Neither 1 nor 2

Answer 1

Correct Answer - Option 3 : Both 1 and 2

CONCEPT:

• Error: The result of every measurement of experiments by any measuring instrument contains some uncertainty. This uncertainty is called error. 
• Systematic errors: The errors that tend to be in one direction only, either positive or negative, and occur due to a systematic problem
• Systematic errors can occur due to many reasons:

1. Instrumental error: Error due to instruments itself
2. Imperfection in experimental technique or procedure: When we did not use an instrument correctly
3. Personal errors: Due to a person's carelessness

EXPLANATION:

• Instrumental error is one of the systematic errors.
• Instrumental errors occur due to errors in the imperfect calibration of the measuring instrument, zero error in the instrument, or imperfect design, etc.
• If we take an example of a thermometer, the temperature graduations of a thermometer may be inadequately calibrated (it may read 104 °C at the boiling point of water at STP whereas it should read 100 °C);
• In another example of vernier calipers:  the zero mark of the vernier scale may not coincide with the zero marks of the main scale.
• Since the reason for the error can be both imperfect design and imperfect calibration of the measuring instrument, So both options 1 and 2 are correct.
• Hence the correct answer is option 3.