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Light and Quantized Energy. Chapter 5 Section 1. Wave Nature of Light. Visible Light is a type of electromagnetic radiation EM radiation is a form of energy that exhibits wavelike behavior as it travels through space. Parts of a Wave. A. D. C. B. Parts of a Wave. A – Crest B – Trough
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Light and Quantized Energy Chapter 5 Section 1
Wave Nature of Light • Visible Light is a type of electromagnetic radiation • EM radiation is a form of energy that exhibits wavelike behavior as it travels through space. • Parts of a Wave A D C B
Parts of a Wave • A – Crest • B – Trough • C – Amplitude – height of a wave from the origin • D – Wavelength (λ) – crest to crest or trough to trough • Frequency (ν) – the number of waves that pass a given point per second (1/s, s-1, Hz)
c = λν • c = the speed of light in a vacuum • 3.00 x 108 m/s • Longer wavelength = lower frequency • Shorter wavelength = higher frequency
Practice Problems • What is the wavelength of a wave having a frequency of 3.76 x 1014 Hz? • What is the frequency of a 6.9 x 10-13 m wave? • What is the wavelength of a 2.99 Hz wave? • What is the frequency of a 7.43 x 10-5 m wave?
Electromagnetic Spectrum • Includes all forms of electromagnetic radiation with the only difference in the type of radiation being λ and ν.
Particle Nature of Light • Quantum – the minimum amount of energy that can be gained or lost by an electron • E = hν • E = energy • h = Planck’s constant = 6.626 x 10 -34 J·s • ν = frequency (Hz)
Practice Problems • What is the energy of a 7.66 x 1014 Hz wave? • What is the frequency of a wave carrying 8.35 x 10-18 J of energy? • What is the wavelength of a 7.65 x 10-17 J wave? • What is the frequency of a 1.31 x 10-22 J wave? What is the wavelength? • What is the energy of a 3.12 x 1018 Hz wave?
Photoelectric Effect • Electrons called photons are emitted from a metal’s surface when light of a certain frequency shines on the surface • Photons – a massless particle that carries a quantum of energy • You find the energy of a photon the same way you found the energy of a quantum • E = hν
Atomic Emission Spectrum • It is the set of frequencies of the electromagnetic waves emitted by atoms of the element.