What is true regarding the calibration of a null indicator instrument like a galvanometer?

In the context of a null indicator instrument such as a galvanometer, stating that calibration of the pointer or needle is not necessary emphasizes the design and function of the instrument. A galvanometer operates on the principle of detecting small changes in current or voltage by moving the pointer in response to an input signal. The critical factor is the instrument's sensitivity to these electrical signals, rather than the physical position of the pointer itself.

As long as the underlying electronics and mechanics of the device remain operational and the zero-reference point is stable, the calibration of the pointer, which reflects the response of the instrument, does not need to occur frequently or at regulated intervals like more complex measuring devices. This aspect allows for practical usage in various environments where fine adjustments to the pointer may not be necessary to ensure accurate measurements, provided that the instrument is maintained in a good working condition.

Other options suggest that frequent calibration or specific attention to the pointer's positioning is essential, which does not align with the operational characteristics of a galvanometer that emphasizes the functionality over the physical calibration of the indicator needle.