What is the importance of reading the liquid level at eye level when measuring a meniscus?

When measuring the meniscus of a liquid, reading the liquid level at eye level is crucial because it helps avoid parallax errors. Parallax error occurs when the measurement is read from an angle rather than directly in line with the meniscus, which can lead to inaccuracies. When the eye is not aligned with the liquid level, it might appear higher or lower than it actually is, which could result in an incorrect measurement. By ensuring that you are at eye level with the meniscus, you can obtain a true reading, which is essential for precision in laboratory measurements.

While consistency in measurements and the ability to compare liquids can also be important factors in scientific work, the primary reason to read at eye level is specifically to eliminate the possibility of parallax errors, which directly impact the accuracy of the measurement.