Name ______
Unit 5 Concept 1 and 2 Notes
Electromagnetic Waves and Light
Electromagnetic Waves
Are ______consisting of changing electric fields and changing magnetic fields
They are able to ______from place one place to another
They differ from mechanical waves in how they are produced and how they travel
Review- how are mechanical waves produced?
How are waves produced?
Mechanical waves ______
Electromagnetic waves are produced by ______
______
Electric field- a region of space that ______on charged particles
Magnetic field- a region of space produced by magnets, changing electric fields and ______
Electromagnetic waves are produced when an electric charge ______
Think: Have you ever been warned to keep magnets away from electronic devices like a laptop? Why is this?
How do electromagnetic waves travel?
Review- mechanical waves need a ______in order to travel
Electromagnetic waves can travel ______
Electromagnetic radiation – the transfer of ______traveling through matter or across space
The Electromagnetic Spectrum
1800- ______used a prism to separate light (by wavelengths)
He wondered if there was a difference in the ______for each color produced
He set up a series of ______
Lowest temperature at the ______end, highest temperature at the ______end
Herschel also discovered that the temperature increased beyond the red light which led him to ______beyond the red end (today we know this is infrared)
Later (1801) ______discovered ultraviolet radiation by experimenting with light exposed to silver nitrate dipped paper
The full range of frequencies of electromagnetic radiation is called the ______
The above diagram shows the full electromagnetic spectrum in order of increasing frequencies
The electromagnetic spectrum includes ______
______
- each is characterized by a ______of wavelength and frequencies
Speed of electromagnetic waves
People tried to measure the speed of light but ______
The speed was thought to be ______
1926- ______measures the speed of light
He placed an 8-sided rotating mirror on top of Mt Wilson (CA) and other mirror on Mt San Antonio 35.4km away
He timed the light beam as it traveled from one mountain to another
Since Michelson, many other scientists have measured light all confirming that light and all electromagnetic waves travel at the ______
______
Speed of light (c) = ______
In a vacuum, all electromagnetic waves travel at the same speed but they are not all the same
Their ______
remember speed is a ______of wavelength and frequency
Speed = wavelength x frequency
Dual nature
Electromagnetic radiation sometimes travels ______and sometimes like ______
1801- ______showed light travels in waves by shining light through slits and observed what happened when it reached a darkened screen
There was ______which only occurs when two or more waves overlap
The photoelectric effect described in ______is the emission of electrons from a ______caused by light striking it
Was puzzling because ______light caused it, but not a brighter red light
1905- ______proposed light consists of small pockets of energy now called photons
Each photon’s energy is ______
______the light
Blue light has a higher ______than red light
Intensity
The rate at which a wave’s energy flows through a given unit of area (______)
The intensity of light ______as photons travel further away from the source
Assignment
p538 Section Review #6, 7, 8, 9