Radiant Energy  

particles or waves of energy emitted Radiation Electromagnetic radiation – energy released from all objects Nuclear radiation – energy released when a nucleus of an atom changes

Electromagnetic Radiation Energy emitted from all atoms when electrons move to different energy levels in an atom Energy is not matter it is a wave

Types of Electromagnetic Radiation Ionizing high energy radiation that produces ions (alpha, beta, gamma) Non-ionizing radiation low energy radiation that doesn’t produce ions

Visible Spectrum

Electromagnetic radiation moves in waves Waves can be described in terms of four characteristics Amplitude Wavelength Frequency speed

Wavelength is distance between crests:  measured in m, cm, mm, m, nm, etc. Amplitude is the height of wave: Intensity of light depends on amplitude measured in m, cm, mm, m, nm, etc. Frequency is how fast the wave oscillates up and down:  measured in cycles/sec. Also called a Hertz (Hz): 1/sec or sec-1 Speed is the speed of light: 3.00 X 108 m/s c

Calculate Green light has a wavelength of 570 nm. What is it’s frequency? What is the color of light that has a frequency of 4.7 x 1014 1/sec? (look in book for color)

Energy, frequency and wavelength are related E= h h= Planck’s constant 6.6262 X 10-34Js

Calculate A certain violet light has a wavelength of 413nm. What is the frequency of the light? What is the energy of the light? = c/ = c/ Convert nm to m  = 3.00X 108m/s = 7.26 X 1014 1/s 413 X 10-9m E= h E=(6.6262 X 10-34 Js)(7.26 X 10141/s) = 4.81 X 10-19J

Light Is a form of electromagnetic radiation Has dual properties Behaves like a wave. Moves through space in waves Behaves like a stream of particles called photons Light is quantized – has a specific energy

Wave nature of light Oscillating electromagnetic fields

Nuclear binding energy E=mc2 Mass is converted to energy Mass proton=1.0078 amu Mass of neutron=1.0087 amu 1J=1 kg m2/sec2 1 amu=1.66 x 10-27 kg

Electromagnetic radiation has energy