General biologyLesson 1 of 2 in the course How We See the Invisible World

Light and Microscopy: Refraction, Lenses, and Image Quality

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

Save course
Lesson progress
0 / 5

Your progress is kept in this browser only.Sign up to save it

Summary

Light is a form of electromagnetic radiation (EMR) that behaves like a wave. Understanding its properties helps explain how microscopes use light to reveal details that are too small to see with the unaided eye.

A light wave has several characteristics. Wavelength is the distance between corresponding points on consecutive waves, such as peak to peak. Amplitude describes the height of a wave’s peak, or the depth of its trough. Frequency is the rate at which a wave oscillates—the number of wave cycles passing a point in a given time.

All flashcards

What is amplitude?
The height of a wave’s peak or the depth of its trough.
What is transmittance?
The proportion of incoming light that passes through a material.
What is focal length?
For parallel incoming rays, the distance from a lens to the focus.
How does fluorescence differ from phosphorescence?
Fluorescence follows absorption almost immediately; phosphorescence is delayed.
How are photon energy and frequency related?
Higher-frequency photons carry more energy.

Quiz questions

  1. What does a material’s refractive index describe?Answer: How much the material slows light relative to its speed in empty space.
  2. When a light ray enters a higher-index material obliquely from a lower-index material, which way does it bend?Answer: Toward the line perpendicular to the boundary.
  3. For parallel incoming rays, what does the focal length of a convex lens measure?Answer: The distance from the lens to the point where the rays converge.
  4. Which visible-light color has the lowest frequency and longest wavelength?Answer: Red.
  5. What distinguishes phosphorescence from fluorescence?Answer: Phosphorescent emission is delayed after absorption.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

More in General biology

All General biology lessons
General biologyLife's Characteristics, Organization, Evolution, and Biological Classification5 flashcards · 5 quiz questions · 4 gamesPlay free →General biologyScientific Inquiry: Reasoning, Experiments, and Research Communication5 flashcards · 5 quiz questions · 4 gamesPlay free →General biologyBiology Foundations: Life, Organization, Classification, Specialties, and Ethics5 flashcards · 5 quiz questions · 4 gamesPlay free →General biologyHuman Reproduction, Fertility, and Family Planning5 flashcards · 5 quiz questions · 4 gamesPlay free →General biologyHistorical Foundations of Cell Theory, Endosymbiosis, and Germ Theory5 flashcards · 5 quiz questions · 4 gamesPlay free →General biologyBiology Foundations: Scientific Inquiry, Research Practice, and Bioethics5 flashcards · 5 quiz questions · 4 gamesPlay free →