NATURE OF WAVES 2000 Microsoft Clip Gallery n

NATURE OF WAVES © 2000 Microsoft Clip Gallery n Waves (Def. ) – A wave is a disturbance that transfers energy. n Medium – Substance or region through which a wave is transmitted. n Speed of Waves – Depends on the properties of the medium.

LIGHT: What Is It? © 2000 Microsoft Clip Gallery Video Light Energy n Atoms n. As atoms absorb energy, electrons jump out to a higher energy level. n. Electrons release light when falling down to the lower energy level. n Photons - bundles/packets of energy released when the electrons fall. n Light: Stream of Photons n © 2000 Microsoft Clip Gallery

Electromagnetic Waves n Speed in Vacuum n 300, 000 km/sec n 186, 000 mi/sec n Speed in Other Materials n Slower in Air, Water, Glass n Speed of Light Video © 2000 Microsoft Clip Gallery

Transverse Waves © 2000 Microsoft Clip Gallery n Energy is perpendicular to direction of motion n Moving photon creates electric & magnetic field n Light has BOTH Electric & Magnetic fields at right angles!

Electromagnetic Spectrum © 2000 Microsoft Clip Gallery

Electromagnetic Spectrum n Visible Spectrum – Light we can see n Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. n Largest to Smallest Wavelength.

Refraction of Light Refraction – Bending of light due to a change in speed. n Occurs when the wave enters a new medium. n Index of Refraction – Amount by which a material refracts light. n Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors. n

Refraction (Cont. ) Video

Reflection of Light n Reflection waves – Bouncing back of light The Law of Reflection states that the angle of incidence equals the angle of reflection n Regular reflection –smooth surfaces scatter light very little. Images are clear & exact. Ex: mirrors n Diffuse reflection – reflected light is scattered due to an irregular surface. Ex: walls n

Video

Diffraction n The bending of waves around a barrier or through an opening. New waves are formed from the original n Light waves diffract much less than sound waves. n

Wave Interference n Two waves combining to form a new wave.

Constructive Interference n Occurs when waves combine to make a wave with a bigger amplitude. Occurs when the crests overlap, they make higher crests n The new amplitude is equal to the net of the amplitude of the two crests that combine. n

Destructive Interference n Occurs when the waves combine to make a wave with a smaller amplitude. Occurs when the Crest of one wave overlaps With the trough of another wave. n If the crest has a larger amplitude than the trough, the crest amplitude decreases and part of it will remain. n If the original waves had equal amplitudes, then the crest and through completely cancel each other out. n