2026 토플 리스닝 입문:
문제 유형과 시험 구성

남자Have you seen the updated syllabus for the philosophy course?

남자I went to the library study room I reserved, and another group was already settled in there.

여자Are you sure you had the right room? The numbers on that floor are confusing.

남자I checked the confirmation: room 204, two to four. They showed me the same room and time on their phones.

여자Then the system double-booked it. Did the front desk move either group?

남자The reservation manager had left, and the student worker said he could only leave a note. My group is already waiting.

여자Is your group doing anything you really need privacy for? The fourth-floor open area is usually quiet now, though it is not a real room.

남자Mostly planning, so it might work for the first hour. I'll try that before everyone gives up, then ask about the mistake when the manager is back.

Graduating students, please note a location change for Saturday's commencement rehearsal. Because rain is expected, rehearsal has been moved from the outdoor amphitheater to the gymnasium inside the Athletics Complex. The time has not changed: check-in starts at ten AM, and rehearsal should last about two hours. Enter through the east doors and stop at the registration table before joining your college's line. Wear comfortable shoes because you'll practice the processional several times. Check the follow-up email before Saturday; it will include a campus map with the gym entrance marked.

So today I want to talk about something you look through every single day without thinking about it — glass. Have you ever wondered why you can see right through a window but not through a wall? Both are solid materials, but only one is transparent. The answer comes down to how light interacts with the atoms inside.

OK, so light travels as tiny packets of energy called photons. When a photon hits a material, the atoms inside can absorb it, but only if the photon's energy matches the gap between the atom's electron levels. In most metals, those gaps are small, so visible light gets absorbed easily, which is why metals look opaque and shiny. In glass, though, the electron energy gaps are unusually large. Visible light photons simply don't carry enough energy to be absorbed, so they pass straight through.

Now, here's a practical example: modern double-glazed windows. Why two layers? Well, while visible light still passes through both panes, the air or special gas trapped between them blocks heat transfer. So the same material that lets you see outside also helps keep the warm air in.

And, in a related way, engineers use this principle in fiber optic cables. They design glass fibers to be extremely clean and uniform, so light signals can travel long distances with very little loss, mainly because the photons are not readily absorbed.