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Humans can see wavelengths from about 700 nm, which appears dark red, to about 400 nm, which appears violet. The light with short wavelengths (violet) carries more energy than the light with long wavelengths (red). In 1704 Sir Isaac Newton published a book called "Opticks" which explained some of the mysteries of light.
Mathematics and experiments show that light is a transverse wave – the electric and magnetic field vectors point in directions that are perpendicular to the direction of motion of the light wave (and as it turns out, they also rare always perpendicular to each other). Figure 3.1.1 – Electromagnetic Wave. The red arrows in the figure above ...
- Introduction
- Sources
- Speed
- Other Characteristics
Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum. The transverse nature of light can be demonstrated through polarization. 1. In 1678, Christiaan Huyg...
Light is produced by one of two methods… 1. Incandescenceis the emission of light from "hot" matter (T ≳ 800 K). 2. Luminescence is the emission of light when excited electrons fall to lower energy levels (in matter that may or may not be "hot").
Just notes so far. The speed of light in a vacuum is represented by the letter c from the Latin celeritas— swiftness. Measurements of the speed of light. Ole Rømer (1644–1710) Denmark. "Démonstration touchant le mouvement de la lumière trouvé par M. Roemer de l'Académie des Sciences." Journal des Scavans. 7 December 1676. Rømer's idea was to use th...
The amplitude of a light wave is related to its intensity. 1. Intensityis the absolute measure of a light wave's power density. 2. Brightnessis the relative intensity as perceived by the average human eye. The frequency of a light wave is related to its color. 1. Coloris such a complex topic that it has its own section in this book. 2. Monochromati...
The change in direction of a beam of light as it travels from one material to another is called refraction. The diagram shows refraction of light passing into, and then out of, a glass block.
Summary. Light and other forms of electromagnetic radiation move through a vacuum with a constant speed, c, of 2.998 × 10 8 m s −1. This radiation shows wavelike behavior, which can be characterized by a frequency, ν, and a wavelength, λ, such that c = λν. Light is an example of a travelling wave.
In Lesson 1, we will investigate the variety of behaviors, properties and characteristics of light that seem to support the wave model of light. On this page, we will focus on three specific behaviors - reflection, refraction and diffraction. A wave doesn't just stop when it reaches the end of the medium. Rather, a wave will undergo certain ...
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By measuring the difference in these time intervals and with appropriate knowledge of the distance between Jupiter and Earth, Roemer calculated that the speed of light was 2.0 ×108 m/s 2.0 × 10 8 m / s, which is only 33% below the value accepted today. Figure 1.2.1 1.2. 1: Roemer’s astronomical method for determining the speed of light.
