Could be a light bulb,
but traditionally it's sunlight via a mirror.
It
IF YOU HAVE A MICROSCOPE THAT DOES NOT HAVE AN INTERNAL LIGHT SOURCE, YOU WILL HAVE TO USE THE EXTERNAL LIGHT SOURCE THAT IS PROVIDED IN THE CABINET WITH THE MICROSCOPE.
Light.
compound light microscope
The Function of a base in a microscope, light microscope that is, is to provide the stage with a light source as well as provide a support for the lens of the Microscope.
The light source of a microscope produces light that passes through the specimen being observed. It can be a bulb, LED, or mirror.
The source of radiation in a dissecting microscope is typically a halogen or LED light bulb. These light sources emit visible light that is used to illuminate the specimen being observed through the microscope.
mirroor
The type of light source that reflects light rays for a microscope is typically a mirror or a prism. These components are used to direct and focus light onto the specimen being viewed through the microscope.
light source
A microscope.
Without the light source, you wouldn't be able to see your sample very well!