Light

Concept 4: Sources of Light

Success Criteria

  • I can describe the different sections of the electromagnetic spectrum and their energy.

  • I can identify examples of light sources and light reflectors.

  • I can explain that light energy can be reflected, transmitted, or absorbed by objects.

  • I can compare transparent, translucent, and opaque objects.

  • I can explain how shadows are formed.

Vocabulary

Energy

Joule

Transformation

Hei mahi

Hei Mahi - Discuss / debate with your neighbour the following statement:

"The moon is a source of light at night because it creates light."

The Electromagnetic Spectrum

Success Criteria: I can describe the different sections of the electromagnetic spectrum and their energy.

C4 Task 1: Choose one of these resources to read.

Resource 1: Grass Level (easy level text)

M9PW C4. Electromagnetic Spectrum - Grass Level Reading.pptx

Resource 2: Sky Level (medium level text)

M9PW C4. EM Spectrum - Sky Level.pdf

C4 Task 2: Complete this worksheet.

M9PW C4. EM Spectrum Worksheet.pdf

Sources of Visible Light

Success Criteria: I can identify examples of light sources and light reflectors.

A light source is an object that can create light.

The most important light source is the sun. Other light sources include:

  • Fire

  • Electric Lights

  • Fireworks

  • Lightning

Light reflecting objects do not create light. We can see them because of the light reflected off of them.

The moon is NOT a light source because it does not create light. We can see the moon because of the sun light reflected off of the moon.

The bottom of the ocean can be so deep that light from the Sun cannot reach it. How can animals survive down there?

Bioluminescence is where organisms are able to create their own light. These organisms are light sources.

C4 Task 3: Read the resource below

M9PW C4. Light Sources - Sky Level.pdf

C4 Task 4: Complete this worksheet.

M9PW C4. Light Sources Worksheet.pdf

How Light Interacts with Objects

Success Criteria:
I can explain that light energy can be reflected, transmitted, or absorbed by objects.
I can compare transparent, translucent, and opaque objects.
I can explain how shadows are formed.

When light hits an object, light can either be:

  • Transmitted - if the object allows light to pass through it.

  • Reflected - if the object reflects (bounces) light off them.

  • Absorbed - if the object absorbs (takes in the) light.

Objects that don't make any light can be classified as:

  • Transparent - if the object lets all light pass through it.

  • Translucent - if the object lets some light pass through it.

  • Opaque - if the object lets no light pass through it.

Shadows are places where light is "blocked" by an opaque object.

C4 Task 5: Read the resource below.

M9PW C4. Light + Objects - Grass Level.pdf

C4 Task 6: Complete all or some of the following activities.

Transparent, translucent, opaque activity.

M9PW C4. Light + Objects Task.pptx

Hands-On Investigations

M9PW C4. Investigating Light + Objects.pdf

Worksheet

M9PW C4. Light + Objects Worksheet.pdf

Concept 5: Reflection

Success Criteria

  • I can describe reflection.

  • I can use the laws of reflection to draw ray diagrams for flat and curved mirrors.

Vocabulary

Energy

Joule

Transformation

Hei mahi

Hei Mahi - Use the mirror in front of you to decode the message on the piece of paper. Write the answer down.

Hei mahi

Hei Mahi - Observe your image as you walk up to BOTH curved mirrors.

1) Which one is concave/convex?

2) How are the images different?

Reflection and Ray Diagrams in Plane and Curved Mirrors

Success Criteria
I can describe reflection.
I can use the laws of reflection to draw ray diagrams for flat and curved mirrors.

Reflection is when light bounces off an object. Ray diagrams are used to show an image of an object reflected in a mirror.

The law of reflection states that "The angle of incidence equals the angle of reflection". So, if a wave hits a mirror at an angle of 36°, it will be reflected at the same angle (36°).

When drawing ray diagrams, make sure you:

  1. Use a ruler.

  2. Indicate the direction of light by using arrows.

  3. Label the incident ray, reflected ray, and normal.

Note: the Normal is a line at right angles to a given line or surface.

Mirrors are either flat (planar) or curved.

Reflection of Light in Plane Mirrors

A plane mirror is a flat mirror. The reflected image in the flat mirror:

  • Is the right way up.

  • Is flipped horizontally.

There are two types of curved mirrors:

  • Convex mirrors have a reflective surface that bulges out.

  • Concave mirrors bulge inward like a cave.

Reflection of Light in Concave Mirrors

The images in a a concave mirror are magnified (larger) and upside down.

Concave mirrors reflect light inwards towards a point called the focus (F).

In concave mirrors, the F is always in front of the mirror.

They’re called “converging” mirrors because they bring the rays together.

Concave mirrors are commonly found in the headlights of vehicles. It makes the light more reflective and wider, making it possible for the drivers to have a better view at night.

Concave mirrors are also used in microscopes and face mirrors to enlarge the view.

Reflection of Light in Convex Mirrors

The images in a a convex mirror are reduced (smaller) and the right way up.

Convex mirrors reflect light outwards. The focus of a convex mirror is behind the mirror.

They’re called “diverging” mirrors because they bring the rays apart.

Convex traffic safety mirrors are designed for road safety to see better at blind corners, concealed entrances and exits. Convex ceiling mirrors are used for surveillance for shops because they allow someone to watch what is going on in a wide area.

C5 Task 1: Read the resource below.

Sky Level (medium level text)

M9PW C5. Reflection - Sky Level.pdf

C5 Task 2: Choose from the following learning activities.

Hands-On Investigations

M9PW C5. Investigating Reflection.pdf

Worksheet

M9PW C5. Reflection Worksheet.pdf

Concept 6: Refraction

Success Criteria

  • I can describe refraction.

  • I can use the laws of refraction to draw ray diagrams for lenses and glass blocks.

Vocabulary

Energy

Joule

Transformation

Hei mahi

Hei Mahi - Write the completed sentences in your notes.

Concave mirrors reflect light ____ towards a point called the ____ point. As rays get close and meet, we call these ____ rays.

Convex mirrors reflect light ____. The ____ point of the convex mirror is ____ the mirror. As the rays separate, we call them ____ rays

Carousel imageCarousel imageCarousel image

Refraction of Light

Success Criteria: I can describe refraction.

When light passes from one substance into another more dense substance it changes direction.

Light travels slower when it enters a dense medium, e.g. from air to glass. It bends towards the normal.

Light travels faster when it enters a less dense medium, e.g. from glass to air. It bends away the normal.

We call this change of direction the refraction of light.

Lenses

Success Criteria: I can use the laws of refraction to draw ray diagrams for lenses and glass blocks.

When light passes through a convex lens, the rays of light all move towards each other (converge).

Convex lenses make an object appear larger than it really is. They are used in magnifying glasses, eyeglasses, cameras, and microscopes.

When light passes through a concave lens, the rays of light all move away from each other (diverge).

Concave lenses make an object appear smaller than it really is. They are used in peepholes, eyeglasses, telescopes, cameras, lasers, and flashlights

The Eye

C5 Task 1: Choose one of the resources to read.

Grass Level (easy level text)

9PW C6. Refraction - Grass Level Reading.pdf

Sky Level (medium level text)

9PW C6. Refraction - Sky Level Reading.pdf

Sun Level (harder level text)

9PW C6. Refraction - Sun Level Reading.pdf

C5 Task 1: Choose from the following learning activities:

Hands-On Investigations

9PW C6. Refraction Investigation - Hands-On.pdf

Worksheet

9PW C6. Refraction Worksheet.pdf

Cow's Eye Dissection - Interactive Website

Safety & Instructions

M9PW C6. Cow's Eye Dissection - Hands-On.pdf

Concept 7: Visible Light

Success Criteria

  • I can list the seven colours of the visible spectrum in order.

  • I can describe what happens when the primary colours of light are added to each other.

  • I can explain how light filters work and how colours appear under different light.

Vocabulary


Hei Mahi:

Hei Mahi in your book/laptop:


What TYPE of energy is detected by your eyes.

Name a SOURCE of this type of energy.


Take one of the coloured papers.

1) Work together to arrange yourselves into a line along the back of the classroom, in order of the colours of a rainbow.

2) Where do rainbows come from?

3) How is each colour different?

The Visible Spectrum of Light

Success Criteria: I can list the seven colours of the visible spectrum in order.

Visible white light from the Sun is made up of seven colours: red, orange, yellow, green, blue, indigo, and violet.

To remember this sequence of colours, you should learn the acronym ROYGBIV.

Each colour of light has a different wavelength, which means it bends (refracts) by different amounts.

Under extreme bending/refraction, the colours are separated.

Which colour has the highest energy?

Which colour has the lowest energy?

How We See Colour

When 'white light' shines on an object, the surface of an object reflects some colours and absorbs others. We perceive (detect/see) the reflected colours.

Black objects absorb all colours. White objects reflect all colours.

M9PW C7. Rainbows - Hands-On.pdf

Hei Mahi:

Hei Mahi in your book/laptop:


How are the primary colours of light different to the primary colours of paint?


Adding Primary Colours of Light

Success Criteria: I can describe what happens when the primary colours of light are added to each other.

The primary colours of light are red, green, and blue.

The secondary colours of light are magenta, cyan, and yellow.

When combined with each other, red, green, and blue make the other colours of the spectrum.

Colour monitors use the colours red, green, and blue in different combinations to make a colour picture.

The close-up view of an LCD TV screen shows red, green, and blue sub-pixels that combine to make colour pictures.

Filters

Success Criteria: I can explain how light filters work and how colours appear under different light.

Filters subtract or absorb different colours of light, and lets other colours through to create coloured light.

For example, a red filter blocks out all colours but red. A magenta filter blocks out all colours but magenta.

Investigation: Adding Light

Aim: To find out what colours are made when red, green, and blue light are added in different combinations.

Equipment: 1 x Light box, light filters (red, green and blue), white A4 paper.

Method:

  1. Set up your light box as per the diagram.

  2. Change the combination of lights shone on the white paper.

  3. Record the resultant colour in your printed table.

Extension: Shadows

Create a shadow using a pen.

Describe and explain the shadow effect you observe

Think of how you could use a labelled diagram to strengthen your answer.