Introduction to Optics

Designed as an introduction to the study of optics for the PSSC program. Some good stuff. The pictures in the swimming pool are terrific. Unfortunately our print is in sad shape colour wise.

brief summary of topics discussed:

(time 0:00)straight line propagation of light

shadow cast by a small source of light

shadow cast by a large source of light

Investigation of sharpness of shadows:

3 sources diameters 0.15, 0.65 2 mm (size measured off camera), examine shadow cast directly on film in camera, smallest source shows diffraction

single slit made from tongue depressors used with linear filament bulb - diffraction

Conclusion - light doesn't travel in straight lines but the effect is small

(9:35) light beam in a smoke box, attempt to influence path with i)beam of light travelling perpendicular; ii)charged rod; iii)magnet - no effect observed

smoke particles affect path of light - scattering - the "second way that light can be bent" (diffraction was the first)

(12:11) reflection = third way that light can be bent

piece of slate at grazing incidence

piece of glass and piece of plastic wrap stretched in a frame to check whether opacity or thickness is important in reflection

(14:07) soap film, dark film at top

(15:27) refraction = fourth way that light can be bent

fish tank

swimming pool, camera underwater, shots of person sitting at side of pool with legs in water

(19:34) fish tank again, small rotatable mirror underwater, critical angle

(21:48) carbon filament lamp with screen, punch holes in screen and combine resulting images by means of a lens (a teaser for future studies)

(22:38) credits