#### 6. Ray Tracing

The principle rays are introduced and students draw scaled ray diagrams to
predict the nature, position, size and orientation of real and virtual images
formed by concave and convex lenses and mirror. Magnification is defined and
this is related to the distance of the image and the object from the lens or
mirror.

*10 cm focal length convex lens and lens holder, 10 cm focal length concave
mirror and mirror holder, Candle, screen, nail or base and stem of slotted
masses, 10 cm focal length concave lens and lens holder, 10 cm focal length
concave mirror and mirror holder, 10 cm focal length convex mirror and mirror
holder Top*

#### 7. The Lens Formula

Students measure the distance of the object and its real image from a convex
lens for a range of object distances. This leads to the discovery of the formula
1/u +1/v = 1/f. The formula is tested and then tested when a vitual image is
formed. The real is positive sign convention is introduced and students learn to
calculate the position and size of an image formed by an object near convex and
concave lenses and mirrors. Calculations are checked using the apporopriate lens
or mirror and using a candle as the object.

*10 cm focal length convex lens and lens holder, 10 cm focal length concave
mirror and mirror holder, Candle, screen, nail or base and stem of slotted
masses. Top*

#### 8. Refraction

Students investigate the saving of a person at the beach and discover the
path across the sand and through the water that will result in reaching the
person in the smallest possible time. They discover 'Snell's Law' concerning the
angles they run and swim when moving along the minimum time path. Using a ray
box and a semicircular plasic block they discover the same law applies to light.
Refractive index is defined and determined for both plastic and water. Students
learn to determine the path light will follow when it passes between any two
substances. They check their calculation by putting the plastic block inside the water tank.

*Ray/light box and single ray mask, Semicircular plastic block, Semicircular water tank, Protractor *
Top

#### 9. Total Internal Reflection and Dispersion

Students discover the conditions needed for TIR to occur and then calculate
the critical angle for a plastic/air boundary. They check the prediction with a
ray box and a plastic block. They calculate the critical angle for a plastic/water boundary
and check their calculation by putting the block into a semicircular water tank. Students then
investigate dispersion and determine the refractive index of the plastic block
when different colours of the spectrum pass through it.

*1 L beaker of water, Small plane mirror/side mirror of the ray/light box
is suitable), Ray/light box, Single ray mask, Semicircular plastic block, Semicircular
water tank and a Protractor Top *

#### 10. The Convex Lens

Students calculate and draw on a large scale diagram, the paths followed by
light through a convex lens. The three ligh paths are parallel to the axis of
the lens. Students measure angles of incidence and calculate angles of
refraction at the air/glass and glass/air boundaries and discover the the
position of the principle focus of the lens. They compare their result with the
the value obtained using the Lens Makers Formula. A very valuable exercise.
Student have been known to say they 'get it better' after completing it.

*Ruler, Protractor * Top

#### 11. The Eye part 2

Students investigate how the eye focusses on objects They use a convex lens
and a screen to model the eye and replace the lens with one of a different shape
when the object is moved. The effect of pupil size and depth of field is
studied. Defects of vision are is investigated and students add additional
lenses to 'defective' model eyes to produce a sharp image on the scrreen for
both long and short sighted eyes.

*Convex lenses with focal lengths of 5, 10, 20 and 50 cm, Concave lens with
focal length of 50 cm, 2 lens holders, Candle and Screen Top *

#### 12. Fire in Diamonds

Students plot paths of light through a large scale diagram of a diamond with
Tolkowski's cut. They discover how to produce the fire effect - the coloured
flash. A diamond ring is set up and the students look at it from the predicted
direction and find the phenomenon called fire in diamonds.
*Ruler, Pacer pencil, Protractor, Ray/light box, Diamond ring, Retort
stand, Bosshead and Clamp Top *

#### 13. The Rainbow

Students plot the path of light through the diagram of a large water drop.
They predict the angle of exit of the light and the angle subtended at the eye
by a rainbow. Students check their calculations using a plastic vial filled with
water and a ray box, and viewing the rainbow formed in a water sprinkler.

*Ruler, Pacer pencil, Protractor, Plastic vial, Ray/light box, 2 icy pole
sticks and a small nut and bolt Top *

#### 14. The Magnifying Glass

In this experiment students construct a 1:2 scale diagram of a person looking
at a spider through a convex lens used as a magnifying glass. The concept of
angular magnification is introduced and students determine the theoretical value
using the scale diagram. Using a spider on a screen, a convex lens and two set
squares students check their prediction by measuring the angular magnification
as seen when looking through the lens. This is repeated for a range of values,
the maximum angular magnification is determined and related to the focal length
of the lens.

*Ruler, 2 set squares, 10 cm focal length convex lens, holder and
screen Top *

Only the left third of the diagram the students construct is displayed.

#### 15. The Compound Microscope

Students use two convex lenses to create a model microscope. They learn how
to make the final image form at the distance of the near point. By putting a
ruler at the near point they can measure the width of the image when looking
into the eyepiece. The theoretical linear magnification is determined and
compared with the value calculated from the measurements. The effect that the
distance between the lenses has on the magnification is investigated.

*Metre ruler and 30 cm ruler, 2 10 cm focal length convex lenses in
holders, Candle, Screen, Retort stand, Bosshead and clamp,
Set square Top *

#### 16. Telescopes

Students trace rays through a diagram of a Keplerian and a Galilean
telescope. The angular magnification produced is related to the focal lengths of
the lenses used. The concept of the eyering is introduced. Students construct
the two telescopes and view an object at the far end of the room. The angular
magnifications produced by the telescopes are determined from a series of
measurements and compared with the focal lengths of the lenses. The advantages
and disadvantages of the Keplerian versus the Galilean type are discussed.

*IEC Laser Optics Show (manufactured by Industrial Equipment and Control
(Australia) 61-63 McClure Street Thornbury Victoria 3071 Australia. ph 61 3 9497
2555 fax 61 3 9497 2166 30, 40, or 50 cm focal length convex lens, 10 cm focal
length convex lens, 2 lens holders, 2 set squares Top*

#### 17. The SLR Camera

Students investigate the following aspects of an SLR camera : method of
focussing, the pentaprism and the focussing screen, field of view, size of
image, focal ratio of the lens, brightness of image, depth of field, exposure
time and ASA of film. They learn how the ASA, focal ratio, and exposure time are
interrelated and how the depth of field can be controlled with suitable
combinations of the three variables.

*SLR camera, 10, 20 and 50 cm focal length convex lenses, 2 Cardboard discs
with diameter 5 cm. One disc needs a 1 cm diameter hole in its centre and the
other needs a 2 cm diameter hole in its centre. Candle, Lens Holder and
Screen Top*

#### 18. Colour Filtration

Students use a computer interface and a light sensor to measure the
percentage transmission of the different parts of the complete spectrum through
different coloured filters and then plot graphs of percentage transmission
versus colour for each filter.

*PC and digital/analog interface (10 bit recommended). Light intensity
sensor, Triangular glass prism with a high lead content (high refractive index),
Stand, Bosshead and clamp, Colour filtration plastic strip printed from the file
supplied, Yellow filter from light box kit, Spectroscope, Ray/light box, 12V
Power Supply, Red, Green, Blue, Yellow, Magenta and Cyan filters **Top*

#### 19. Colour Photography

Students are introduced to the primary colours and their coresponding
complimentary colours. Students then go through the process of producing a
colour print from a colour negative. They are given a scene and imagine taking a
picture of it. They use coloured pencils to fill in the the coloured dyes in the
different colour sensitive layers on the film and the printing paper that are
produced when they are developed. They colour in the negative and then colour in
the print after analysing which parts of the complete spectrum pass through the
different combinations of dyes. Senior students really enjoy this exercise. They
learn how the colours of a scene are reproduced on a print and they do some
colouring - something they haven't done for ages! A Colour transparency file of
completed diagrams included.

*Ray/light box, 12V power supply, Red, Green, Blue, Yellow, Magenta and
Cyan filters, Red, green, blue, yellow, magenta, cyan (Derwent no.41) and black
pencils, Spectroscope or IEC Laser Optics Show Top*