How does visible light interact with an object

Light travels slower in air than in a vacuum, and even slower in water. As light travels into a different medium, the change in speed bends the light. Different wavelengths of light are slowed at different rates, which causes them to bend at different angles. Wave Behaviors. Retrieved [insert date - e. Science Mission Directorate. National Aeronautics and Space Administration. Wave Behaviors Light waves across the electromagnetic spectrum behave in similar ways. For example, when the full spectrum of visible light travels through the glass of a prism, the wavelengths are separated into the colors of the rainbow.

Electromagnetic Spectrum Series Series Homepage. Infrared Waves. Reflected Near-Infrared. Visible Light. Ultraviolet Waves. Earth's Radiation Budget. Diagram of the Electromagnetic Spectrum.

Recommended Articles. September 24, Solar Eclipse - June 10, June 09, Aurora-Chasing Citizen Scientists Help Inclusive Outreach. Inclusive Science Outreach. Resources and Initiatives for outreach practitioners and scientists pursuing inclusive, effective science outreach.

Incubator Blog. About RockEDU. Connecting science and scientists with teachers, students, and classrooms to improve science for all! Search All Pages. Search Classroom Resources. Select All Clear. Save to Google Drive. Your download is opening in a new tab. Certain materials can refract nonvisible forms of EMR and, in effect, transform them into visible light. Certain fluorescent dyes, for instance, absorb ultraviolet or blue light and then use the energy to emit photons of a different color, giving off light rather than simply vibrating.

This occurs because the energy absorption causes electrons to jump to higher energy states, after which they then almost immediately fall back down to their ground states, emitting specific amounts of energy as photons. Not all of the energy is emitted in a given photon, so the emitted photons will be of lower energy and, thus, of lower frequency than the absorbed ones. Thus, a dye such as Texas red may be excited by blue light, but emit red light; or a dye such as fluorescein isothiocyanate FITC may absorb invisible high-energy ultraviolet light and emit green light Figure 7.

In some materials, the photons may be emitted following a delay after absorption; in this case, the process is called phosphorescence. Glow-in-the-dark plastic works by using phosphorescent material. Microscopes magnify images and use the properties of light to create useful images of small objects. Magnification is defined as the ability of a lens to enlarge the image of an object when compared to the real object.

Greater magnification typically improves our ability to see details of small objects, but magnification alone is not sufficient to make the most useful images. It is often useful to enhance the resolution of objects: the ability to tell that two separate points or objects are separate. A low-resolution image appears fuzzy, whereas a high-resolution image appears sharp.

Two factors affect resolution. The first is wavelength. Shorter wavelengths are able to resolve smaller objects; thus, an electron microscope has a much higher resolution than a light microscope, since it uses an electron beam with a very short wavelength, as opposed to the long-wavelength visible light used by a light microscope.

The higher the numerical aperture, the better the resolution. Even when a microscope has high resolution, it can be difficult to distinguish small structures in many specimens because microorganisms are relatively transparent.

It is often necessary to increase contrast to detect different structures in a specimen. Various types of microscopes use different features of light or electrons to increase contrast—visible differences between the parts of a specimen see Instruments of Microscopy. Additionally, dyes that bind to some structures but not others can be used to improve the contrast between images of relatively transparent objects see Staining Microscopic Specimens. You place a specimen under the microscope and notice that parts of the specimen begin to emit light immediately.

Skip to main content. How We See the Invisible World. Search for:. The Properties of Light Learning Objectives Identify and define the characteristics of electromagnetic radiation EMR used in microscopy Explain how lenses are used in microscopy to manipulate visible and ultraviolet UV light.

Clinical Focus: Nathan, Part 1 Nathan, a year-old counselor at a summer sports camp, scraped his knee playing basketball 2 weeks ago. What are some things we can learn about these bacteria by looking at them under a microscope? Think about It If a light wave has a long wavelength, is it likely to have a low or high frequency? If an object is transparent, does it reflect, absorb, or transmit light?

Think about It Explain how a lens focuses light at the image point. Name some factors that affect the focal length of a lens. Think about It Which has a higher frequency: red light or green light? Explain why dispersion occurs when white light passes through a prism. Why do fluorescent dyes emit a different color of light than they absorb? Read this article to learn more about factors that can increase or decrease the numerical aperture of a lens. Think about It Explain the difference between magnification and resolution.

Explain the difference between resolution and contrast. Name two factors that affect resolution. Key Concepts and Summary Light waves interacting with materials may be reflected , absorbed , or transmitted , depending on the properties of the material. Light waves can interact with each other interference or be distorted by interactions with small objects or openings diffraction.

Refraction occurs when light waves change speed and direction as they pass from one medium to another. Differences in the refraction indices of two materials determine the magnitude of directional changes when light passes from one to the other.

A lens is a medium with a curved surface that refracts and focuses light to produce an image. Visible light is part of the electromagnetic spectrum ; light waves of different frequencies and wavelengths are distinguished as colors by the human eye.

A prism can separate the colors of white light dispersion because different frequencies of light have different refractive indices for a given material. Fluorescent dyes and phosphorescent materials can effectively transform nonvisible electromagnetic radiation into visible light.