Unit 5 Concept 1 and 2 Notes

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