断面

だんめん

cross section

JLPT N1

Character Breakdown

Understanding 断面 (Cross Section)

The word 断面 (だんめん) refers to the surface or shape revealed when an object is cut through. It is commonly used in scientific, engineering, and everyday contexts to describe the internal structure visible from a cut.

Usage and Context

断面 is often used when discussing materials, biology (like tree rings), architecture, and engineering. For example, looking at the cross section of a tree reveals its age through growth rings. In architecture, 断面図 (cross-sectional diagrams) help explain internal layouts.

Common Collocations

  • 断面図 (だんめんず): cross-sectional diagram, used in technical drawings.
  • 断面積 (だんめんせき): cross-sectional area, important in physics and engineering.
  • 断面を調べる: to examine the cross section, often for material properties.

Register and Nuance

断面 is a formal, technical term mostly used in academic, scientific, or professional settings. It is not commonly used in casual conversation unless discussing specific topics.

Learner Tips

A common confusion is mixing 断面 with 表面 (ひょうめん, surface). 断面 specifically means the cut surface inside an object, while 表面 means the outer surface. Remember 断面 involves a 'cut' or 'section' to reveal inside structure.

Example Sentences

このきのだんめんをみると、ねんりんがはっきりとわかります。

If you look at the cross section of this tree, you can clearly see the growth rings.

だんめんずをつかってたてもののないぶこうぞうをせつめいします。

I will explain the internal structure of the building using a cross-sectional diagram.

このだんめんはきんぞくのきょうどをしらべるためにじゅうようです。

This cross section is important for examining the strength of the metal.