Final answer:
The claim that a galvanometer is used to study eye movements is false. A galvanometer detects and measures electrical current and is not designed for tracking eye movements.
Step-by-step explanation:
The statement that a galvanometer is used to study eye movements while a respondent reads advertising copy is false. A galvanometer is an instrument used to detect and measure electrical current by employing a needle deflection caused by the magnetic force on a current-carrying wire. It can be adapted for various measurements in electrical circuits, for example, as a component in potentiometers and voltmeters. However, it is not designed to track eye movements. Technologies utilized for tracking eye movements include eye-tracking cameras and software, not galvanometers.
When it comes to the accuracy of null measurements, factors that might affect it include the precision of the instrument, external magnetic fields, temperature variations, and the skill of the operator. Using a digital device that is more sensitive than a galvanometer could potentially improve the accuracy of such measurements.