Light , Arsenie

Light travels almost unimaginably fast and far. Light carries energy and information. Light travels in straight lines. Light bounces and bends when it comes in contact with objects. Light has color. Light has different intensities, it can be bright or dim. Light is not an electromagnetic wave and it can travel through empty space. Light is comprised of units called photons. They have no mass. They carry the energy and force of light. Properties and Sources of Light

Speed of Light c = f Wavelength (m) Frequency (Hz) Speed of light 3 x 10 8 m/sec

The speed of light 300 million meters per second The speed at which light travels through air is approximately 300 million meters per second. 3 x 10 8 m/s. Light travels almost a million times faster than sound.

electromagnetic wavesThe energy field created by electricity and magnetism contains electromagnetic waves. electromagnetic spectrumVisible light is only a small part of the energy range of electromagnetic waves. The whole range is called the electromagnetic spectrum and visible light is in the middle of it. The Electromagnetic Spectrum

Since color is related to energy, there is also a direct relation between color, frequency, and wavelength. Color and Vision white light When all the colors of the rainbow are combined, we do not see any particular color. We see light without any color. We call this "white light".

Calculate! Calculate the wavelength in air of blue- green light that has a frequency of 600 X 1012 Hz

Rainbows A rainbow is caused by light being refracted once in droplets of water We see the constituent colors because they disperse through the water in the air- the droplets act like a prism Double rainbow? Why?/How? Yes- colors inversed

LCD Projectors/ TVs or Digital Cameras The white light from a light source is split into red/green and blue components using mirrors or a chip that only transmit that specific wavelength. Each green/red and blue beam then passes through a dedicated LCD panel made up of thousands of minuscule pixels. An electrical current turns pixels on or off to create different “shades” of each color The three colors are then recombines by a prism and projected through the projector lens.

Human Eye

So how do we see colors? The color of an object originates on the surface of the apple. We see the color of an object because that object reflects “a color” to the eye. Every color is the effect of a specific wavelength. All other colors of the spectrum are absorbed. In the case of the apple, we see the color red because the red apple reflects the specific wavelength of red (640nm is red).

Dogs vs. Humans

Is black a color? Is white a color?

Mirrors Reflect, Lenses Refract lensA lens is an optical device that is used to bend light in a specific way. convergingA converging lens bends light so that the light rays come together to a point. divergingA diverging lens bends light so it spreads light apart instead of coming together.

prismA prism is like a lens in that it refracts light. It is another optical device that can cause light to change directions. –A prism is a solid piece of glass with flat polished surfaces. It will disperse beams of light into their constituent colors (the rainbow). MirrorsMirrors reflect light and allow us to see ourselves. –Images appear in mirrors because of how light is reflected by mirrors. Mirrors Reflect, Lenses Refract

Law of Reflection The angle of incidence equals the angle of reflection. The incident ray strikes the mirror. The reflected ray bounces off.

Index of refraction index of refraction The ability of a material to bend rays of light is described by the index of refraction (n). Light follows the path of least TIME through different materials. This is not the same as the shortest distance.

Angle of Refraction and Snell’s Law The mathematical equation that relates angle of incidence, index of refraction, and angle of refraction is called Snell’s Law.