Waves light quanta
Sponsored Links
This presentation is the property of its rightful owner.
1 / 17

Waves, Light & Quanta PowerPoint PPT Presentation


  • 78 Views
  • Uploaded on
  • Presentation posted in: General

Waves, Light & Quanta. Tim Freegarde. Web Gallery of Art; National Gallery, London. Circumference of the earth. (Tropic of Cancer). Eratosthenes of Cyrene (276-195 BC). 5000 stadia ~ 5000 x 180m = 900 km. α = β ~ 1/50 circle. Radius astronomicus. Reinerus Gemma-Frisius , Leuven.

Download Presentation

Waves, Light & Quanta

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Waves, Light & Quanta

Tim Freegarde

Web Gallery of Art; National Gallery, London


Circumference of the earth

(Tropic of Cancer)

Eratosthenes of Cyrene (276-195 BC)

  • 5000 stadia ~ 5000 x 180m = 900 km

  • α = β ~ 1/50 circle


Radius astronomicus

Reinerus Gemma-Frisius, Leuven

  • measurement of celestial angular distances


Camera obscura

Reinerus Gemma-Frisius, Leuven

de radio astronomica et geometrica, 1545

  • solar eclipse, 24 Jan 1544


Pinhole camera

image

object

pinhole

foil

screen


a

b

x

x

0

L

Rays

S

S

  • light travels in straight lines

  • shortest distance between two points

B

C

A

P

P


1.

light travels in straight lines

The nature of light

light travels between two points by the shortest distance


a

P=S

  • equal angles:

b

x

x

0

L

Rays

S

S

  • light travels in straight lines

  • shortest distance between two points

B

C

A

P

P


P

b

a

P=S

  • equal angles:

b

P

x

x

0

L

Reflection

S

S

  • light travels in straight lines

  • shortest distance between two points

P

P


S

P

P=S

  • equal angles:

Reflection at a curved surface

  • light travels in straight lines

  • shortest distance between two points

  • suppose we design a surface so that all routes are the same length…?


S

S

P

P

Conic sections

focus B

focus

focus A

PARABOLA

ELLIPSE

directrix


S

P

P=S

  • equal angles:

Concave mirror

  • light travels in straight lines

  • shortest distance between two points

f

R

  • equal times to focus


Hugo of Provence

Nicholas of Rouen

Lenses and refraction

Ibn al-Haytham ‘Alhazen’

(965-1039)

Tommaso da Modena (1325-1379)

Chiesa San Nicolò, Treviso


a

b

x

x

0

L

Fermat’s principle of least time

S

S

B

C

A

P

P

  • refraction at a plane surface

Pierre de Fermat (1601-1665)


a

b

x

x

0

L

Pierre de Fermat (1601-1665)

Fermat’s principle of least time

S

S

  • light rays follow the path of least time between two points

P

P

  • refraction at a plane surface


a

b

x

x

0

L

Willebrord Snel van Royen

(Leiden, 1580-1626)

Snell’s law of refraction

S

S

  • light rays follow the path of least time between two points

P

P

  • refraction at a plane surface


1.

light travels in straight lines

The nature of light

light travels between two points by the shortest distance

light travels between two points by the quickest route (least time)

light travels between two points by the route for which the time taken is a stationary value


  • Login