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Answer For Diagnostic
1. R- Pain receptors, P- Touch receptors, S-
Pressure receptors
2. Sensation, regulation, or protection.
3. Thickness of epidermis, concentration of
sensory cells.
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Light
Speed of light 3.0 x 10^8 m/s
Or 300,000km/s
Can travel through vacuum (electromagneticwave) can travel without medium.
Properties of light: travel in straight line
Prove: the formation of shadow, eclipse ofsun, and eclipse of moon.
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Light Travelling in Straight Line
The Prove for light travelling in a straight line:
- the formation of shadow
- the eclipse of the sun- the eclipse of the moon
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Shadow
(A small light source dont produce
Umbra and Penumbra)
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Umbra and Penumbra
(the shadow from a large light source)
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Application of the properties of light
Sundails make use of shadows to tell time
A sundial is a device that measures time by theposition of the Sun. In common designs such asthe horizontal sundial, the sun casts a shadowfrom its style onto a surface marked with linesindicating the hours of the day. The style is thetime-telling edge of the gnomon, often a thin rodor a sharp, straight edge. As the sun moves across
the sky, the shadow-edge aligns with differenthour-lines. All sundials must be aligned with theaxis of the Earth'
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Horizontal Sundails
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The sundial dates back to the Egyptian Period,
around 1500 B.C. It was also used in ancient
Greece and Rome. In central Europe it was the
most commonly used method to determine
the time, even after the mechanical clock was
developed in the 14th century. The sundial
was actually used to check and adjust the timeon mechanical clocks until late into the 19th
century
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Transparent, Translucent, Opaque
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Stereoscopic vision
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Stereoscopic Vision Used when both eyes are used to view an object
Human beings and predators (tigers, dogs, owls,cats etc)
Animal with stereoscopic vision- both eyes in the
front of their head Advantage of stereoscopic:
To see things in three dimensions
To estimate distance accurately
Large field of stereoscopic vision
Helps predators to pounce accurately on their prey
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Monocular vision
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Monocular vision is used when we look at things
only with one eye
Herbivorous animals such as cows, zebras, deer and
horses have mainly monocular vision.
Advantage: can see a large area (to detectpredators)
Disadvantage: cannot judge distance accurately,
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Devices to Overcome the Limitations
of Sight
Eyes are not perfect, can not see in any
condition
I F i
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Instrument Function
Magnifying Glass It is a biconvex lens with short focal length
It enlarges an object for viewing
Microscope It use two biconvex lenses- the objective lens and
the eyepiece lens
It is used to magnify very tiny specimens such as
cells and microorganisms
Binoculars They are used to see objects which are far away e.g.
to watch horses running in a race
Periscope It is used by submarines to see what is above the
surface of the sea. It is also used to see things on
the other side of a wall
X-ray machine It is normally used in hospitals to take pictures e.g.
to detect any fracture in bones or injury in the body
An x-ray of the chest is taken to detect tuberculosis
of the lungs
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Ultra sound
scanning machine
It is a machine which scans the internal organs of
the body such as the gall bladder and liver
Contact lens Some people wear contact lenses instead if
spectacles to correct their eye sight
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Periscope
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Sound can travel through solids, liquids and
gases.
Sound can travel at about
5000 m/s in solids
1300 m/s in liquids
300 m/s in air
D t th ti l i lid i l l t
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Due to the particles in solid is closely compact,
the vibration of sound can be pass (propagate)
quickly from one particle to particle.
There is no sound travelling pass vacuum,
because sound need medium to propagate.
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