Question

What is parallax error ?​​​​

Answer 1

A parallax error is the perceived shift in an object's position as it is viewed from different angles. The error is most easily noticed by looking at a nearby object with one eye closed, then looking at it through the other eye. The apparent motion of the object is the parallax shift, and it is responsible for a small, but noticeable, error common to optical equipment. what causes this:

Incorrect angle of viewingthe reading on the scale.

For example, the reading on this beaker will be correctly measured when viewed from the second position of the eye, the other two eye positions will give incorrect readings as can be clearly seen in the image below. This error due to incorrect viewing angle is called Parallax Error.