Deflection magnetometer is an instrument used to measure the magnetic moment and polar strength of a bar magnet. It is also used to compare the pole strengths of two bar magnet.

A deflection magnetometer consists of a small magnetic needle pivoted at the center of a graduated circular scale. Two light aluminum pointers are attached perpendicularly to its two sides to note its deflection.

In magnetometer, the pointer is made of a paramagnetic substance, because paramagnetic substances develop feeble magnetisation in the direction of magnetising field.

Thats why we use,aluminium to make magnetometer pointer.