Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to make a galvanometer [title] Select a compass. [step] A compass has a magnetic needle. This needle will allow you to detect electrical currents because electrical currents generate a magnetic field (and this field interacts with the needle).

Ending1: A compass device is ideal for all sizes. It should not be too small or too small to allow you to move the compass around for a long time. Ending2: The most effective compass will be one meant for navigational purposes (i.e. designed to align to the earth's magnetic field and point north), rather than a toy. Ending3: Consider your compass's specific orientation to determine what direction to see radiographic instances of direction you want your galvanometer to follow. [substeps] The magnetic needle will determine the direction of the galvanometer that you choose. Ending4: A good rule of thumb is to use a compass that is at least 50 volts, although some others require 20 volts. [substeps] Use a compass that you can easily recognize.

Answer format: ending1/ending2/ending3/ending4