When can the parallax error occur during an experiment?

Parallax error can occur during an experiment when the observer's eye is not aligned with the measurement scale or indicator, leading to a misreading of the value. This often happens with instruments like rulers, thermometers, or pressure gauges where the scale is viewed from an angle rather than straight on. Consequently, the reading may appear higher or lower than the actual value, affecting the accuracy of the results. To minimize parallax error, it's important to ensure that measurements are taken at eye level and directly in line with the scale.