Lights wave nature

Maxwell is considered by many physicists to be the 19th-century scientist with the greatest influence on 20th-century physics. His contributions to the science are considered by many to be of the same magnitude as those of Isaac Newton and Albert Einstein.[5] In the end of millennium poll, a survey of the 100 most prominent physicists, Maxwell was voted the third greatest physicist of all time, behind only Newton and Einstein.[6] On the centennial of Maxwell's birthday, Einstein himself described Maxwell's work as the "most profound and the most fruitful that physics has experienced since the time of Newton."[7] Einstein kept a photograph of Maxwell on his study wall, alongside pictures of Michael Faraday and Newton.[8]


2. Light as a transverse wave motion


Demonstration of polarisation using polaroids or other suitable method.

Polaroid film is made of long macromolecules that allow light to travel if it is parallel to the direction of the macromolecules

Applications of Polarisation

Stress polarisation.

Polaroid sunglasses.

3D Glasses AVATAR

2 cameras on set, one the left for the left eye and the other the right. Depth perception requires 2 eyes (stereo).

The polaroid glasses we use in the cinema are right & left circularly polarised light.

Get the 3d glasses and look through the, into a mirror..... what do you notice? maybe look through 1 eye at a line.

Hint mirrors revers the circular handedness of polarisation.

3. Dispersion

Dispersion by a prism and a diffraction grating.

the diffraction grating formula

grating constant

d = the distance between 2 consecutive lines (slits)

so we will find that different diffraction gratings will have a different number of liness etched into 1mm.

The distance 'd' is then found by dividing 1 by the number of lines per mm ...

problem this gives us the value in mm ... in Physics we only deal in meters. So divide this value by 1000 (there are 1000mm in 1m)

n = number (order) of the image

Recombination by a prism.

Demonstration.Rainbows, polished gemstones.Colours seen on surfaces of compact discs.4. ColoursColor is the perceptual quality of light.

(Color is a subjective response by the brain to light stimulating the retina.)

Two visual regions have the same color if a difference between them cannot be perceived by the average human eye.

The human eye can distinguish nearly ten million colors.

Color as a visual response should not be confused with the "color" of a pigment, which is the color one would see when viewing that pigment under typical lighting conditions.

What colours can you see in the bar above

What is Black ? In terms of light?

What is White ? In terms of light ?

Primary, secondary and complementary colours.

the Primary colours are the Green Red & Blue that are shown in the diagram as the large coloured disks. Where they overlap leads to secondary colours of Magenta, Cyan and Yellow, if the 3 overlap then white light is given out

Addition of colours.

The painter's color wheel is a historical artifact that refuses to die. The primary colors are not red, yellow, and blue. Painters and art teachers promote this scheme. It is a convenient way to understand how to mimic one color by mixing red, yellow, and blue. But these colors do not satisfy the definition of primary colors in that they can't reproduce the widest variety of colors when combined. Cyan, magenta, and yellow have a greater chromatic range as evidenced by their ability to produce a reasonable black. No combination of red, yellow, and blue pigments will approach black as closely as do cyan, magenta, and yellow.

Pigment colours need not be considered.


Stage lighting, television.

a revision of so much of the light course

5. Electromagnetic spectrum

Relative positions of radiations in terms of wavelength and frequency.

Detection of UV and IR radiation.

Detect IR & UV.

Prism. Lamp. Screen. Microscope slide. Petroleum jelly. Thermopile. thermometer with a blackened bulb

Infrared Vision

Rattlesnakes and other pit vipers use their eyes to see during the day. But at night they use infrared sensory organs to detect and hunt warm-blooded prey. These infrared "eyes" are cuplike structures that form crude images as infrared radiation hits a heat sensitive


Get a TV remote, It uses Infra red to communicate, this cannot be seen by the naked eye but it can be seen on the screen of a digital camera.

Infrared cameras:

• medical applications

• night vision.

Ultraviolet and ozone layer.

Greenhouse effect.

6. The spectrometer