1. Electromagnetic Waves
9th Grade Science Chapter 13A
Electromagnetic Waves

2. Electromagnetic Waves
Magnetic Field
Area around a magnet where the magnet can be detected
Produced by magnet OR moving electric charge

3. Electromagnetic Waves
Electric Field
Area around a charge where the charge can be detected
Charges move due to the field

4. Electromagnetic waves
Caused by moving electric charge
Perpendicular electric and magnetic waves
Motion of both fields is perpendicular to direction of travel of wave

5. Electromagnetic wave Properties
Transfer of energy:
EM fields interact with other charges and move them
Speed:
Travel at m/s in vacuum
Written as 3 x 108 m/s
Travels more slowly through medium

6. Electromagnetic Waves
Particle/wave duality:
Photoelectric effect observed by Heinrich Hertz in 1887
Requires minimum frequency of light
Intensity of light affects amount of electricity produced, but not IF light is produced
Light is not behaving like a wave!

7. Electromagnetic waves
Photoelectric effect:
Max Plank (1901):
Amount of energy related to frequency of a wave
Amount called quantum
Albert Einstein (1905):
Light carries ‘packets’ of energy depending on frequency
Photon
Light behaves as both wave AND as particle!

8. Duality of Nature Analysis of motion shows:
All moving objects move as both particles and waves
The bigger the particle, the less like a wave
Newtonian Mechanics
The smaller the particle, the more like a wave
Quantum Mechanics