According to application, instruments are classified as

According to the application, instruments are classified into types.

Switch board and Panel Instruments:

- Measuring instruments for switchboards have a square or a rectangular front

- The pointers and scales for these instruments should be so that the position of the pointer is conspicuous, the scale markings are legible and there is a contrast with the background

- Pointers are usually broad or carry broad targets as their ends

- Aluminium strip or tube is used for making pointers

- The scale is generally printed on the enamelled surface of a metal plate or on paper or cardboard pasted to a metal plate

- These types of instruments should be mounted in a vertical position

Portable Instruments:

- These usually have knife-edge pointer moving over scale marked with fine lines

- If the pointer and scale are in different planes, observational errors may result on account of parallax

- These parallax errors can be avoided by using knife-edge pointers and scales mounted in the same plane as a tip of the pointer

Both 1) and 2)