Prepared by:
Ridwan Abrar
Junior Year Undergrad Student
Department of EEE, BUET
Precautions in LED experiments:
1. Hard to judge when LED lights
2. No repeated results
3. Should have checked/measured wavelengths
Sources of error in electricity experiments:
1. Systematic/ zero error on voltmeter
2. Parallax error of analogue meter
3. Random error in voltmeter reading
Precision list of instruments:
Digital vernier calliper or Micrometer Screw gauge: 0.01 mm
Vernier calliper: 0.1 mm
Stopwatch = 0.01 s. However, note that there is uncertainty in starting
and stopping the stopwatch.
Improving accuracy:
● Repeating readings and calculating average
● Taking readings at eye level to avoid parallax error
● Holding the apparatus vertically
● Releasing from rest (if it involves releasing something)
● Checking for zero error
● Excluding anomalous values
** If the question mentions or hints any particular value of precision for these instruments,
please follow that and do not use the precision values written above
Precautions to take while measuring diameter of coins:
1. Take readings from different orientations and at right angles and then an average is
calculated
2. Micrometer is checked for zero error
Measuring diameter of a coin by using 10 coins at a time:
Prepared by Ridwan Abrar
, 1. Measuring 10 gives average for all coins
Or, Measuring one coin several times across different diameters gives an average
2. One coil may be abnormal or all coins may not be identical
Safety precaution in Young Modulus experiments:
1. Masses might fall on the foot. So boots must be worn
2. Risk from breaking spring, so wear goggles
Uncertainties unbound:
Calculating uncertainty:
● Obvious anomalies should be in both mean and uncertainty
● Range/2
● Highest value - Mean
When the % difference between two values is greater than the total
experimental uncertainty, then the experiment is not acceptable.
Calculation of percentage uncertainties:
Prepared by Ridwan Abrar
Ridwan Abrar
Junior Year Undergrad Student
Department of EEE, BUET
Precautions in LED experiments:
1. Hard to judge when LED lights
2. No repeated results
3. Should have checked/measured wavelengths
Sources of error in electricity experiments:
1. Systematic/ zero error on voltmeter
2. Parallax error of analogue meter
3. Random error in voltmeter reading
Precision list of instruments:
Digital vernier calliper or Micrometer Screw gauge: 0.01 mm
Vernier calliper: 0.1 mm
Stopwatch = 0.01 s. However, note that there is uncertainty in starting
and stopping the stopwatch.
Improving accuracy:
● Repeating readings and calculating average
● Taking readings at eye level to avoid parallax error
● Holding the apparatus vertically
● Releasing from rest (if it involves releasing something)
● Checking for zero error
● Excluding anomalous values
** If the question mentions or hints any particular value of precision for these instruments,
please follow that and do not use the precision values written above
Precautions to take while measuring diameter of coins:
1. Take readings from different orientations and at right angles and then an average is
calculated
2. Micrometer is checked for zero error
Measuring diameter of a coin by using 10 coins at a time:
Prepared by Ridwan Abrar
, 1. Measuring 10 gives average for all coins
Or, Measuring one coin several times across different diameters gives an average
2. One coil may be abnormal or all coins may not be identical
Safety precaution in Young Modulus experiments:
1. Masses might fall on the foot. So boots must be worn
2. Risk from breaking spring, so wear goggles
Uncertainties unbound:
Calculating uncertainty:
● Obvious anomalies should be in both mean and uncertainty
● Range/2
● Highest value - Mean
When the % difference between two values is greater than the total
experimental uncertainty, then the experiment is not acceptable.
Calculation of percentage uncertainties:
Prepared by Ridwan Abrar
