Slides in this set

Slide 1

Preview of page 1

OCR GCSE Physics P7
Topic 4: Stars…read more

Slide 2

Preview of page 2

Hot Objects and Electromagnetic
· Stars release electromagnetic radiation as well as radio waves and x-rays
· If the light is at the red end of the spectrum, then the star is cool
· If the light is at the violet/white end of the spectrum it is very hot
· The hotter the star the greater the luminosity
· The hotter the star, the peak frequencies is greater ­ produces more
radiation of higher frequencies…read more

Slide 3

Preview of page 3

Electron Energy Levels
· Electrons in an atom can only have certain values of energy (energy levels)
· When an electron drops from one energy level to another it loses energy
· The this happens a photon is emitted (this is light)
· The energy of a photon is equal to the difference between the energy levels
· The greater the energy gap, the greater the energy of the photon
· High energy photons correspond to high frequency, short travelling
wavelength light…read more

Slide 4

Preview of page 4

Electrons and Line Spectra
· Darks lines appear in line spectra's when electrons absorb energy from
white light
· White light consists of photons with all possible values of energy
· An electron in a low energy level can only absorb a photon whose energy is
just right to life it to a higher energy level. When one has been absorbed it
jumps to a higher energy level
· The white light is now missing a photon
· The missing photon corresponds with the dark lines in the spectra…read more

Slide 5

Preview of page 5

Formation of a Star
· The star begin as a large clouds of
dust, helium and hydrogen
· These clouds are called interstellar
gas clouds or a nebula
· Gravity makes the nebula contract, this
causes the cloud to heat up
· This is know as a protostar
· When the cloud gets hot enough
hydrogen nuclei start to fuse to form
helium nuclei
· This is called nuclear fusion
· When energy is released as light and
electromagnetic radiation, it is then a
star…read more

Slide 6

Preview of page 6

The Structure of the Sun
· The core is 14 million K (Kelvin).
This is where fusion of hydrogen
takes place
· Radiation (photons) travels
outwards through the radiative
zone. This carries out heat to the
· The photosphere emits
electromagnetic radiation…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9

Slide 10

Preview of page 10
Preview of page 10


No comments have yet been made

Similar Physics resources:

See all Physics resources »