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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

so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
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
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit 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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