electromagnetic induction

understanding, comprehension / appreciation

physics (as an area of study)

to study / to learn

Principle. / A fundamental truth that bases on. / An eternal law that is common over lots of fact. / (philosophy) A basic fact which explains why something exists.

the above / the top (position or direction) / the surface of / superior in skill, age, level, etc.

in addition; furthermore / on top of (which)

understand, comprehend / appreciate

important, significant

importance, consequence, significance