Class Notes (809,631)
Canada (493,758)
Physics (299)
PHYS 183 (60)
Tracy Webb (34)
Lecture 16

Lecture 16

2 Pages
Unlock Document

McGill University
PHYS 183
Tracy Webb

PHYS 183 – The Milky Way Inside and Out – Tracy Webb Winter 2013 Lecture 16: February 11 , 2013  there is an internal battle in the sun between pressure and gravity  it is easy to change a neutron to a proton at a subatomic level by simply changing the quarks  fission is how a nuclear bomb works  fusion requires very high temperatures  at low speeds, electromagnetic repulsion prevents the collision of nuclei  at high speeds, nuclei come close enough for the strong force to bind them together  nuclear fusion in the sun o the sun’s core is a sea of nuclei & free electrons moving very fast o because of the high temperature the sun’s core can fuse 4 H into 1 He nucleus o this releases energy via E = mc o energy comes from the sun fusing together protons to form a new element  proton-proton chain o 2 protons fuse together to make deuterium (H isotope; 1 proton, 1 neutron)  occurs twice o deuterium & proton fuse to make He-3 (He isotope; 2 protons, 1 neutron)  occurs twice o 2 He-3 nuclei fuse to form He-4 (2 protons, 2 neutrons)  releases 2 excess protons o output = gamma ray + neutrinos o all of the missing mass leaves through neutrinos & positrons  how does energy get out of the sun? o nuclear fusion generates gamma-rays (very high energy) in the core o sun’s interior is so dense that photons continually bump into electrons on the way out o with each collision the photon & electron share energy so that by the time the photons reach the outside of the sun they mirror the temperature of the gas o this takes thousands of years o this is called radiative diffusion  how can we know what is happening inside the sun?  solar neutrinos o neutrinos
More Less

Related notes for PHYS 183

Log In


Don't have an account?

Join OneClass

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

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.