A diode is a device which allows current flow through only one direction. That is the current should always flow from the Anode to cathode. The cathode terminal can be identified by using a grey bar as shown in the picture above.

For 1N4004 Diode, the maximum current carrying capacity is 1A it withstand peaks up to 30A. Hence we can use this in circuits that are designed for less than 1A. The reverse current is 5uA which is negligible. It can withstand reverse voltage peak up to 400V.

Features:

• Average forward current is 1A
• Non-repetitive Peak current is 30A
• Reverse current is 5uA.
• RMS reverse voltage is 280V
• Peak repetitive Reverse voltage is 400V
• Available in DO-41 Package

Supplier link: https://components101.com/asset/sites/default/files/component_datasheet/1N4004-datasheet.pdf