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Natural sciences

Grade 8

Energy: electricity, heat and light

Module 11

Reflection and refraction of light

  • LIGHT is another common type of energy.
  • You parents or educators would like to have "eyes at the back of their heads" or would like you to believe that they see everything. We know that this is impossible, though, and for a simple reason.

Activity:

To determine the terms and concepts that relate to light

[lo 2.1, lo 2.3, lo 2.4]

Light travels along a straight line.

Light can change direction, though, and this happens in two ways:

  • Refraction
  • Reflection

REFLECTION: We are going to look at reflection as it occurs with mirrors.

When a beam of light arrives at a certain angle, it will be reflected at the same angle.

ANGLE OF INCIDENCE = ANGLE OF REFLECTION

Activity:

To establish concepts relating to reflection [lo 2.4]

Assignment 1:

1. Draw a sketch of a mirror, showing the angle of incidence and the angle of reflection. Use a protractor.

Assessment of the Sketch

Has the sketch been drawn correctly?

[LO 2.4]

Curved mirrors

Curved mirrors have many applications. They enlarge or diminish and distort the image. A curved mirror can be CONCAVE. This will CONVERGE light beams towards a fixed point, the FOCUS.

Other mirrors may be CONVEX . They will cause light beams to DIVERGE (spread apart). This scales down the image. An application of this is evident in the rear view mirror of a motor car or in wing mirrors.

The same effect can be achieved with polished metals.

Assignment 2:

1. Try the following:

Polish the surface of a large serving spoon to get it to shine.

Look at your own image in the concave and on the convex side of the spoon and compare the shape of the reflections.

Draw the differences in the spaces that are provided:

Concave Convex

Draw convergent and divergent beams from the right to add to the following sketches. Get your educator to help you.

Assessment of Sketches

Were you able to complete the sketches 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

Assignment 1:

LIGHT

  • LIGHT is another common type of energy.
  • You parents or teachers would like to have "eyes at the back of their heads" or would like you to believe that they see everything. We know that this is impossible, though, and for a simple reason
  • Light travels along a straight line. Light can change direction, though. This can be achieved in two ways:

REFLECTION:

  • We see this happening in the case of mirrors.

When a beam of light arrives at a certain angle, it will be reflected at the same angle.

Angle of incidence = angle of reflection

CURVED MIRRORS

  • Curved mirrors have many applications.
  • They enlarge and distort images.
  • A mirror could be C ONCAVE
  • It will CONVERGE light beams towards a fixed point, the FOCUS.
  • Other mirrors may be CONVEX .
  • They will cause light beams to DIVERGE (spread apart)
  • This scales down the image.
  • An application of this is evident in the rear view mirror of a motor car or in winged mirrors.

  • Try the following:
  • Polish the surface of a large serving spoon to get it to shine.
  • Look at your own image in the concave and in the convex side of the spoon and compare the effect of the shape on the reflections.

Draw the differences in the spaces that are provided:

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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
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
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
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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