A is the eyepiece (or ocular lens), B is the objective lenses, C is the iris diaphragm, D part is refers to light condenser, E is the location of fine adjustment knob and F is the location of coarse adjustment knob.
Explanation:
A is the eyepiece (or ocular lens), B is the objective lenses, C is the iris diaphragm, D part is refers to light condenser, E is the location of fine adjustment knob and F is the location of coarse adjustment knob. All these parts are the important parts of microscope which has a specific function in the microscope. Without one of these parts, we can not see the microbes in the microscope.