NICET - Highway Construction Inspection Practice Exam

When measuring with a steel tape, what affects the accuracy if the tape is calibrated for different temperatures?

1. Length of the tape

2. Tension on the tape

3. Potential shrinkage of the tape

4. Humidity in the air

The correct answer is: Potential shrinkage of the tape

When measuring with a steel tape that is calibrated for different temperatures, the potential shrinkage of the tape is a significant factor affecting accuracy. Steel tapes are manufactured with a specific coefficient of expansion, which means that they will expand or contract based on temperature changes. If a tape is calibrated at one temperature and used at a different temperature without accounting for this expansion or contraction, the measured length will be inaccurate. For instance, if a tape measures accurately at 20 degrees Celsius and is then used at a much colder or hotter temperature without any adjustments, it may become shorter or longer, respectively, due to temperature-induced shrinkage or expansion. Therefore, for precise measurements, it's crucial to consider the calibration temperature of the tape in relation to the environment in which it is being used, making potential shrinkage a vital factor in ensuring measurement accuracy.