Transcript Section 1 Electromagnetism_slides

PC20312 Wave Optics
Section 1:
Electromagnetism and
Waves
Electromagnetic spectrum
André-Marie Ampère
(1775-1836 )
Carl Friedrich Gauss
1777-1855
Images from Wikipedia
Michael Faraday
1791-1867
James Clerk Maxwell
1831-1879
Images from Wikipedia
E
B
k
Image adapted from Nick Strobel's Astronomy notes at www.astronomynotes.com
John Henry Poynting
(1852-1914)
S = -1 E × B
The Poynting vector is where a
beam of light is pointing.
Image from Wikipedia
Plane wavefronts
Planar surfaces of constant phase
k
E = E0 exp[i(kr-wt)]
Motion in +k
direction
Plane wavefronts
Planar surfaces of constant phase
E = E0 exp[i(kr+wt)]
Motion in -k
direction
k
Pierre de Fermat – 1608-72
Images from Wikipedia
Christiaan Huygens – 1629-95
Huygens’ wavelets
Click to Huygens’ wavelets demo
Or go to
http://www.acoustics.salford.ac.uk/feschools/waves/diffract3.htm
Fig 1.1 Snell’s Law by Fermat
Image courtesy of A. Pedlar
Fig 1.2 Law of reflection by Fermat
P
Tutorial problem:
• Write optical path
length, L, between S
and P as function of x
dL
• Find
dx
S
h2
h1
dL
0
• i = r when
dx
i
r
x
l-x
l
Fig 1.3 Refraction at a spherical surface
A

S
P
C
So
si
Imaging with a curved surface
S3
P2
S1
S2
C
P1
P3
Fig 1.4 Imaging with a lens
n1
n2
Image formed by 1st
surface acts as a virtual
object for 2nd surface
n1
S
P
P'
Si,2
So,2
d
So,1
Si,1