Electromagnetism is a part of physics that studies the interaction between electricity and magnetism.

He is good at solving geometry problems.

He is an expert in toxicology and conducts many studies.

He is an expert in mythology and gave a lecture on the gods of ancient Greece.

He is an expert in bibliography and has many publications.

He is an expert in sociology.

Phonetics is a part of linguistics that studies the physical, physiological, and psychological aspects of sounds.

He is majoring in mineralogy at university.

He is an expert in entomology, especially knowledgeable about butterflies.

Cytology is a branch of biology that studies the structure and function of cells.