1. Physics 1051: Lecture 4: Slide 1 Light Introduction

2. Physics 1051: Lecture 4: Slide 2 Light -- an Electromagnetic Wave

3. Physics 1051: Lecture 4: Slide 3 Electromagnetic Wave Transverse Traveling oscillating electric field and magnetic field Can travel through space Generated by accelerated charges Emitted by excited atoms when they return to ground state

4. Physics 1051: Lecture 4: Slide 4 Electromagnetic Spectrum

5. Physics 1051: Lecture 4: Slide 5

6. Physics 1051: Lecture 4: Slide 6 Visible Part of Spectrum 7 4

7. Physics 1051: Lecture 4: Slide 7 Spring Model Electrons can be modeled as particles connected to the atomic nucleus by springs Electrons of atoms in glass have certain natural frequencies of vibration

8. Physics 1051: Lecture 4: Slide 8 Light Transmission

9. Physics 1051: Lecture 4: Slide 9 Glass Transparency Ultraviolet matches natural frequency of electrons in glass Infrared vibrates entire atom or molecule Both result in warming of the glass

10. Physics 1051: Lecture 4: Slide 10 Opaque What does it mean for an object to be opaque? Light is absorbed without being re- emitted.

11. Physics 1051: Lecture 4: Slide 11 Umbra to Penumbra

12. Physics 1051: Lecture 4: Slide 12 Solar Eclipse

13. Physics 1051: Lecture 4: Slide 13

14. Physics 1051: Lecture 4: Slide 14

15. Physics 1051: Lecture 4: Slide 15 Moon’s Orbit is Tilted

16. Physics 1051: Lecture 4: Slide 16 The Eye