Radiant Energy

particles or waves of energy emitted Electromagnetic radiation – energy released from

all objects

Nuclear radiation – energy released when a nucleus of an atom changes

Radiation

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

Ionizinghigh energy radiation

that produces ions(alpha, beta, gamma)

Non-ionizing radiationlow 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-1Speed 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 energyMass proton=1.0078 amuMass of neutron=1.0087 amu1J=1 kg m2/sec2

1 amu=1.66 x 10-27 kg

Electromagnetic radiation has energy