Formative assessment marking key Light module quiz

Commonwealth of Australia, 2003 1

This marking key is constructed so that it can be used for formative purposes. Possibleanswers to each question are provided. These answers show different levels of conceptualdevelopment from low (*), medium (**) to high (***). This information can be used in aformative manner to match students’ levels of conceptual development to activities ofappropriate conceptual challenge designated by one, two or three stars. Some questionsonly provide opportunity for students to respond at the lower levels of conceptualdevelopment.

1. A man is sitting in a room with a cat. The room has no window and the door is closed. The only source of light is an electric light globe.

When the light is switched on:a. How does the light help the man see the cat?

You may wish to draw arrows on the diagram to help explain.

When the light is switched off and there is no light in the room:b. Can the man see the cat? Explain.c. Can the cat see the man? Explain.

Level ofconceptual

developmentTypical student response at this level

(a) Light from the globe bounces off the cat into the man’s eye.(b) No. You can’t see without light.(c) No. Cats can’t see without light.

(a) Draws light ray arrows on the diagram to show light from theglobe reflecting off the cat into the man’s eye.

(b) No. Light rays are needed to form an image in the eye.(c) No. Light rays are needed to form an image in the eye.

Formative assessment marking key Light module quiz

Commonwealth of Australia, 200

2. Jordan and Kylie are looking into a mirror.

a. Can Jordan see an image o

You may wish to draw arrow

b. Can Kylie see an image of th

Level ofconceptual

development(a) Yes. Li

Jordan(b) No. Th

(a) Yes. CJordan

(b) Construmirror a

(a) Ray diapoint wthe ligh

(b) Ray diareflectio

Jordan

Mirror

3 2

f the box in the mirror? Explain.s on the diagram to help explain.

e box in the mirror? Explain.

Typical student response at this level

ght from the box can bounce off the mirror into’s eye so he can see it.e light from the box won’t reflect back to Kylie.

onstructs light rays to show reflected light enabling to see the box.cts light rays to show light from the box strikes thend reflects away from Kylie.

gram shows light from the box striking the mirror at ahere equal angles of incidence and reflection allowt to reach Jordan’s eye.gram constructed with equal angles of incidence andn.

Kylie

Formative assessment marking key Light module quiz

Commonwealth of Australia, 2003 3

3. The rear view mirror in your car has been broken and you need to make a temporaryrepair. You only have access to a spherical (round) concave mirror and a sphericalconvex mirror. Would either of these be suitable? Explain.

Level ofconceptual

developmentTypical student response at this level

The convex mirror would be better than the concave mirror asconvex mirrors produce upright images and convex mirrorsproduce upside down images.

Draws a ray diagram to show parallel rays being focused by themirror to form an image.

Images produced by spherical mirrors are not the same distancefrom the mirror as the object and therefore do not give a trueindication of how far away the object is.

A flat/plane mirror is ideal as it produces an upright image as farbehind the mirror as the object is in front of the mirror and thereforegives a true indication of how close the car behind is to you.

4. Convex lenses are used in many optical instruments eg cameras, projectors andmagnifying glasses.a. What effect does a convex lens have on light rays?b. Complete the diagram below to show how a convex lens can be used to burn a

piece of paper.

Level ofconceptual

developmentTypical student response at this level

(a) Convex lenses bend light rays so they converge to apoint/focus.

(b) Draws a ray diagram to show how a convex lens convergesparallel light rays to a point.

Formative assessment marking key Light module quiz

Commonwealth of Australia, 2003 4

5. When sunlight shines through the corner of an aquarium the light rays are bent. a. Complete the diagram to show the path of the light ray.

b. Explain why light rays bend when they pass from one medium to another (eg fromair to glass), striking the boundary between the two media at an angle.

c. When white light passes through the corner of an aquarium or through a glassprism a spectrum of colours may be formed. Why does white light break up intocolours under these circumstances?

Level ofconceptualdevelopment

Typical student response at this level

(c) Different colours bend different amounts and therefore whitelight breaks up into its colours as it comes out of a prism.

(a) Diagram shows the ray bends away from the surface(towards the normal) as it enters the water, and towards thesurface (away from the normal) as it leaves the water.

(c) Draws a ray diagram to show differential bending.

(b) Light travels more slowly in glass than in water. When thelight strikes the surface at an angle the rays that hit theglass first are slowed down before the other rays. Becausethe different rays travel at different speeds the bundle ofrays bend.

(c) Different wavelengths/colours travel at different speeds in(optically dense) media such as glass and water (ie differentcolours have a different refractive index). As differentcolours travel at different speeds in glass, when white lightstrikes the surface of glass, the light disperses into itscolours, red light bends (refracts) least and violet the most,thus producing a spectrum.

Formative assessment marking key Light module quiz

Commonwealth of Australia, 2003 5

6. Design an optical instrument that can be used to look up over a wall and project animage on to a screen. Draw a diagram to show the parts of the instrument and thepath along which light will travel through the instrument.

Level ofconceptual

developmentTypical student response at this level

Designs an instrument that will work.

Draws a ray diagram that correctly shows the effect of the mirrorsand lens.