There are several ways to distinguish the positive and negative poles of a power adapter.

Check the logo of the adapter itself: usually the adapter's shell or interface will have ‘+’ or ‘-’ marking, indicating positive and negative poles.

Check the output voltage of the adapter's marking: common positive and negative marking is the output voltage of the ‘+’ and ‘-’ sign.

Use a multimeter to measure: set the multimeter to DC voltage, contact the output terminals of the adapter with the positive and negative terminals respectively, and judge the voltage reading according to the positive and negative. Positive voltage is positive, negative voltage is negative.

Power adapter

Check the instruction manual: The instruction manual that comes with the adapter will usually have a positive and negative indication.

Observe the shape of the adapter interface: usually the positive and negative interfaces have different shapes, the positive interface is in the concave needle type, the negative for the outer cylinder type.

In short, it is important to recognise the positive and negative poles of the power adapter, so as not to damage the device when using it. Be sure to carefully observe and identify before use.