Class Notes (921,883)
CA (542,687)
UTSG (45,909)
AST (668)
AST101H1 (417)
Lecture

# Chapter 5

5 Pages
104 Views

Department
Astronomy & Astrophysics
Course Code
AST101H1
Professor
Clifford Orwin

This preview shows pages 1-2. Sign up to view the full 5 pages of the document.
Unit 5 – Light and Matter
How do we Experience Light:
Energy that light carries is called radiative energy.
Energy and Power:
In astronomy we are concerned more with the rate of energy transfer not the amount of
energy transfer
Rate of energy flow is called power and is measured in units called watts. (1 watt = 1
joule/s)
How do Light and Matter Interact:
Emission: bulb emits visible light. The energy of the light comes from electrical potential energy
supplied to the light bulb.
Absorption: when you place your hand near a light bulb, your hand absorbs some of the light,
and this absorbed energy warms your hand.
Transmission: Some forms of matter, such as glass or air, transmit light, which means allowing
it to pass through
Reflection/scattering: light is able to bounce off of matter, leading to what we call reflection
(bouncing all in the same general direction) or scattering (when the bouncing is more random)
Materials that transmit light are transparent, and opaque if they absorb light.
Many materials are never perfectly transparent or opaque.
All the information that light brings to earth from the universe was encoded by one of the
four basic interactions between light and, matter common to our everyday experience.
Particles and Waves in Everyday Life:
A particle of mater can sit still or it can move from one place to another.
In essence, a particle is a thing, while a wave is a pattern revealed by its interaction with
particles.
Wavelength: distance from one peak to the next (one trough to the next)
Frequency: number of peaks passing by any point each second.
www.notesolution.com
Cycles per second often are called hertz (Hz)
Speed of the waves tell you how fast the peaks travel
Formula defined as: wavelength x frequency = speed
Light as an Electromagnetic Wave:
Light is a wave but not your conventional wave where it moves through a medium. In a
sense light is its own medium
We can describe the forces that charged particles exert on one another in terms of electric
and magnetic fields.
Light waves are vibrations of both electric and magnetic fields caused by the motions of
charged particles. (this we say that light is an electromagnetic wave)
All light travels through empty space at the same speed – the speed of light
Very important relationship between wavelength and frequency for light: the longer the
wavelength, the lower the frequency, vice versa.
Photons:Particles of Light
Light behaves as both a wave and a particle. So, we say that light come in “pieces called
photons.
Each photon of light carries a specific amount of radiative energy. The shorter the
wavelength of light, the higher the energy of photons.
What is the Electromagnetic Spectrum?
There is light that the human eye cannot see. Why? Visible light that splits into the
rainbow of colour is only a tiny part of the complete ranges of light’s wave lengths.
www.notesolution.com

#### Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Unit 5 Light and Matter How do we Experience Light: Energy that light carries is called radiative energy. Energy and Power: In astronomy we are concerned more with the rate of energy transfer not the amount of energy transfer Rate of energy flow is called power and is measured in units called watts. (1 watt = 1 joules) How do Light and Matter Interact: Emission: bulb emits visible light. The energy of the light comes from electrical potential energy supplied to the light bulb. Absorption: when you place your hand near a light bulb, your hand absorbs some of the light, and this absorbed energy warms your hand. Transmission: Some forms of matter, such as glass or air, transmit light, which means allowing it to pass through Reflectionscattering: light is able to bounce off of matter, leading to what we call reflection (bouncing all in the same general direction) or scattering (when the bouncing is more random) Materials that transmit light are transparent, and opaque if they absorb light. Many materials are never perfectly transparent or opaque. All the information that light brings to earth from the universe was encoded by one of the four basic interactions between light and, matter common to our everyday experience. Particles and Waves in Everyday Life: A particle of mater can sit still or it can move from one place to another. In essence, a particle is a thing, while a wave is a pattern revealed by its interaction with particles. Wavelength: distance from one peak to the next (one trough to the next) Frequency: number of peaks passing by any point each second. www.notesolution.com
More Less

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Unlock Document

Unlock to view full version

Unlock Document
Notes
Practice
Earn
Me

OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Just a few more details

So we can recommend you notes for your school.