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Natural sciences

Grade 8

Energy: electricity, heat and light

Module 12

The refraction of white light

Activity:

To investigate the refraction of white light [lo 2.1, lo 2.4]

Splitting up of white light:

  • This phenomenon can be demonstrated in the classroom by directing a beam of light through a PRISM. A prism is a triangular bar of glass or perspex. When this is done, you will see that white light is a combination of all the colours of the rainbow – this range of colours is known as the SPECTRUM.
  • Red, having the longest wavelength, will experience the least refraction. Blue light, on the opposite side of the SPECTRUM , having the shortest wavelength, will show the greatest degree of refraction.

Assignment 1:

Ask your educator to demonstrate refraction.

Complete the sketch that follows by using coloured pencils to indicate the spectrum.

Assessment of the Sketch of the Spectrum

Were you able to complete the sketch correctly?

[LO 2.1]

Spectacles relieve the problems of people who suffer from short-sightedness or long-sightedness.

Assignment 2:

Differentiate between:

Near-sightedness:

L ong-sightedness:

The lenses of spectacles can be like the reflective surfaces you learnt about earlier, convex or concave. These lenses are shaped on both sides and are therefore biconvex or biconcave.

This shape is __________________________________________

Draw these lenses, showing the refraction that results from each type of lens. You might need to ask your educator’s help.

Assessment of the Sketch of the Spectrum

Were you able to complete the sketch correctly?

[LO 2.4]

Assessment

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

  • recalls meaningful information;
  • interprets information;

2.4 applies knowledge.

Memorandum

SPLITTING UP OF WHITE LIGHT:

Assignment 1:

  • This phenomenon can be demonstrated in the classroom by directing a beam of light through a PRISM.
  • A prism is a triangular bar of glass or perspex.
  • When this is done, you will see that white light is a combination of all the colours of the rainbow – this range of colours is known as the SPECTRUM .
  • The different colours that are combined to form white light do not move at the same speed.
  • Red, having the longest wavelength, will experience the least amount of refraction. Blue light, on the opposite side of the SPECTRUM , having the shortest wavelength, will show the greatest degree of refraction.

Complete the sketch that follows by using coloured pencils to indicate the spectrum.

Spectrum colours:

Violet, blue, green, yellow, orange, red

  • Spectacles relieve the problems of people who suffer from shortsightedness of farsightedness .
  • NEAR-SIGHTEDNESS : People with this condition can see close objects well, but objects in the distance are unclear.
  • LONG-SIGHTEDNESS : People with this condition can see distant objects clearly but find it difficult to focus on nearby objects and find reading difficult, for instance. Older people, in particular, develop this problem.
  • The lenses of spectacles can be shaped, like the reflective surfaces about which you have learnt earlier, to be convex or concave. These lenses are shaped on both sides and are therefore biconvex or biconcave .

This illustrates a biconcave lens

  • Further possibilities:
  • Lens refraction
  • Pinhole camera and binoculars

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
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Source:  OpenStax, Natural sciences grade 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
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