The Energy of Light Video Lessons

Concept: The Energy of Light

# Problem: Medical applications of electromagnetic radiation cover the entire spectrum, from gamma rays used to diagnose and treat cancer, to radio waves used in magnetic resonance imaging (MRI). Until recently the tools did not exist to exploit the range from 0.1 to 10 THz, leading some to call this region of the spectrum from 0.1 to 10 THz the “terahertz gap.” But that gap is starting to close as new techniques are developed to explore the terahertz region of the spectrum (Chemistry &amp; Engineering News, 2015, 93, 10-14). It was discovered the terahertz light causes groups of water molecules to coalesce and disassemble repeatedly, and because water permeates most biological studies, terahertz spectroscopy holds considerable promise as important new tool in medical science. A. Calculate the energy (in J) of a 2.4 THz photon.(1 THz = 1 x 1012 Hz = 1 x 1012 s -1 )    Convert your answer above from J to kJ/mol.    B. Calculate the wavelength (in nm) of a 2.4 THz photon.   Do you expect 2.4 THz light to be dangerous to biological tissue? Explain your reasoning.

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###### Problem Details

Medical applications of electromagnetic radiation cover the entire spectrum, from gamma rays used to diagnose and treat cancer, to radio waves used in magnetic resonance imaging (MRI). Until recently the tools did not exist to exploit the range from 0.1 to 10 THz, leading some to call this region of the spectrum from 0.1 to 10 THz the “terahertz gap.” But that gap is starting to close as new techniques are developed to explore the terahertz region of the spectrum (Chemistry & Engineering News, 2015, 93, 10-14). It was discovered the terahertz light causes groups of water molecules to coalesce and disassemble repeatedly, and because water permeates most biological studies, terahertz spectroscopy holds considerable promise as important new tool in medical science.

A. Calculate the energy (in J) of a 2.4 THz photon.

(1 THz = 1 x 1012 Hz = 1 x 1012-1

B. Calculate the wavelength (in nm) of a 2.4 THz photon.

Do you expect 2.4 THz light to be dangerous to biological tissue? Explain your reasoning.