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Chapter 27 Physics

QuestionAnswer
how does light affect things? light is the only thing you see, all visible objects either reflect or emit light, most of what we see is reflected light
what are sources of light? sun, lamp, candle, glowing gases
what is transparent and opaque? some materials let light pass through-transparent (glass, air, water) most things don't let light pass at all-opaque (wood, metal)
what is translucent? some things let light pass through in diffused directions (thin paper, frosted glass)
what do scientists now agree about light? it has a dual nature, part particle and part wave
what are some early ideas of light? light has been studied for thousands of years, greek philosophers thought it was particles that entered the eye and created vision others-streamers or filaments emitted from eye made contact with objects
what did newton think? up until the 1600s thought light was particles that traveled in straight lines
what did huygens think? light was waves and beams could pass through each other like waves do but people still believed newton
what did t young do? showed light could be spread out like waves (diffraction) and wave theory was accepted, 19th century
what did einstein do? photo electric effect, consists of particles (mass less bundles of electromagnetic energy packaged in bundles called photons) move as waves
what did michelson do? discovered speed of light to be 300,000 km/s, using spinning mirror, 1st american-nobel prize
what did galileo do? tried to measure speed of light with lanterns
what did roemer do? astronomer who studied moons of jupiter to learn about speed of light
what is the speed of light? universal constant "c"
what are some speeds and times for light to travel different places? around earth 7.5 times in one second, 8 minutes for light from the sun to reach earth, 4 years for light from the nearest star (AlphaCentauri), the distance light can travel in one year at 300,000km/s is called a lightyear
what is the electromagnetic spectrum? consists of radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays
what is light? energy that is given off by an accelerating electric charge (e-)
how does this energy travel? a wave that is partly magnetic and partly electric-electromagnetic wave, light is only one kind of electromagnetic wave, range-electromagnetic spectrum
helpful hints-electromagnetic spectrum left side longer wavelength-lower energy, right side-higher frequency, more energy
what is the lowest frequency of light we can see? highest? red, violet
what speed do electromagnetic waves travel at? they all travel at the same speed-the speed of light, but they are different in their frequencies and wavelengths
what is infrared? electromagnetic waves of frequencies lower than the red of visible light, heat lamps
what is ultraviolet? electromagnetic waves of frequencies higher than those of violet, sunburns
Created by: distler