## Crave the wave – science olympiad student center wiki gas 85 vs 87

Other types of waves include surface waves and torsional waves. Surface waves are waves that travel along the boundary of two media. The particles in a surface wave move in a circular motion. Torsional waves twist and spin. It is like a screw being drilled or moving your arms back and forth while keeping them flat.

The electromagnetic field is a combination of the magnetic field and the electric field. All EM waves are transverse in nature. They all travel at the speed of light, [math]c = 3.00 \times 10^8 \frac{m}{s}[/math]. That means [math]\lambda \propto \frac{1}{f}[/math], as [math]v = \lambda f[/math] and [math]v = 3.00 \times 10^8 \frac{m}{s}[/math]. The photon energy of a wave is measured in joules and electron volts and can be calculated as follows: [math]e = hf = \frac{ch}{\lambda}[/math] where h = Planck’s constant = [math]6.62607 \times 10^{-34} Js[/math]. Radio waves are the waves with the least energy, longest wavelength, and smallest frequency. These can be split up into AM waves, FM waves, short radio waves, telemetry/millimeter-waves, and terahertz waves. Next are microwaves which are used in microwaves to heat food and infrared waves which humans emit. After that are visible light waves which things like lava emit. Ultraviolet rays are next. Then come x-rays and gamma rays which have the highest energies.

The primary colors of light are red, green, and blue, and the secondary colors of light are yellow, cyan, and magenta. Conversely, the primary colors of pigments are yellow, cyan, and magenta, and the secondary colors of pigments are red, green, and blue.

Dichroic filters have little reflective cavities which resonate with specific wavelengths. Using destructive interference, the wavelengths are canceled out, leaving the rest of the wavelengths to pass through. They are used for precise scientific work since their exact color range can be controlled. Interference filters are more expensive and more delicate.

Neutral Density Filter: Attenuate all wavelengths of visible light, optical density is the common logarithm of the transmission coefficient, which is [math]amplitude_{initial}:amplitude_{incident}[/math] or [math]intensity_{initial}:intensity_{incident}[/math], make photographic exposures longer

Spectra are an application of the visible light spectrum to specific materials. Since certain materials have a unique absorption spectrum and emission spectrum associated with them, spectra can be used to identify unknown materials. They can also be used to learn more about materials at a microscopic level, including things such as molecular structure, crystal structure, and purity.

Absorption spectra represent the portions of the spectrum that consist of wavelengths of incident radiation absorbed by the material. They are helpful in chemical analysis of stars (determining what they are made of and what quantity). Here is an example absorption spectrum. Emission spectra represent the portions of the spectrum that are emitted from a material when electrons from the atom are excited (e.g., from being heated). They are helpful in determining the composition of stars. Here is an example emission spectrum.

Absorption and emission spectra are very closely related, and there are theoretical models that exist where an absorption spectrum can be used to calculate a theoretical emission spectrum, and the other way around. However, this process is beyond the scope of Crave the Wave, so this task is unlikely to be on a test; however, tests may ask what these spectra can be used for, so it is important to know that this technique exists.

• [math]\theta_1[/math] is the angle between the incident ray and the normal, [math]\theta_2[/math] is the angle between the refracted ray and the normal, [math]v_1[/math] is the velocity of light in the first medium (white), [math]v_2[/math] is the velocity of light in the second medium (blue), [math]n_1[/math] is the refractive index of the first medium (white), [math]n_2[/math] is the refractive index of the second medium (blue).

• [math]\lambda[/math] is the wavelength, [math]y[/math] is the perpendicular distance from a point P on a nodal or antinodal line to a point on the central antinodal line, [math]d[/math] is the distance between the slits or sources of light, [math]m[/math] is the order value of the line P is on, [math]L[/math] is the distance from point P to the sources of light.

• A diffraction grating splits and diffracts light into many beams traveling in different directions and results in a characteristic rainbow-ish coloration. A grating typically has ridges on its surface. The grating equation relates the grating spacing and the angles of incident and diffracted light beams.

• [math]E[/math] is the energy of a photon, [math]h[/math] is Planck’s constant (approximately [math]6.626*10^{-34} joule*s[/math], c is the speed of light (approximately [math]2.998*10^8 \frac{m}{s}[/math], [math]\lambda[/math] is the wavelength