1. ELECTROMAGNETIC RADIATION subatomic particles (electron, photon, etc) have both PARTICLE and WAVE properties Light is electromagnetic radiation - crossed electric and magnetic waves: Properties : Wavelength,  (nm) Frequency,  (s -1, Hz) Amplitude, A constant speed. c 3.00 x 10 8 m.s -1

2. Electromagnetic Radiation

3. ELECTROMAGNETIC RADIATION

4. c = C = speed of light, a constant (3.00 x 10 8 m/s) = frequency, in units of hertz (hz, sec -1 ) = wavelength, in meters Electromagnetic radiation propagates through space as a wave moving at the speed of light.

5. Example: Red light has = 700 nm. Calculate the frequency,. = 3.00 x 10 8 m/s 7.00 x 10 -7 m  4.29 x 10 14 Hz = c Wave nature of light is shown by classical wave properties such as interference diffraction Electromagnetic Radiation

6. Diffraction of a Wave

7. Wave Interference Pattern

8. E = h E = Energy, in units of Joules (kg·m 2 /s 2 ) h = Planck’s constant (6.626 x 10-34 J·s) = frequency, in units of hertz (hz, sec -1 ) = frequency, in units of hertz (hz, sec -1 ) The energy (E ) of electromagnetic radiation is directly proportional to the frequency ( ) of the radiation.

9. ELECTROMAGNETIC RADIATION

10. Photoelectric effect demonstrates the particle nature of light. Number of e - ejected does NOT depend on frequency, rather it depends on light intensity. No e - observed until light of a certain minimum E is used. Photoelectric Effect Albert Einstein (1879-1955)