Intermediate 1 Physics

1
Intermediate 1 Physics

• Radiations

• Light

• X-Rays

• Gamma Rays

• Infrared and Ultraviolet

2
Intermediate 1 Physics

• Radiations

Light
3
Light

• Lasers
• Sunlight looks white but it is made up of many
  c _ _ _ _ _ _ combined together.
• A laser is a source of light that is made up of
  o _ _ single colour.
• A laser beam does not s _ _ _ _ _ out -
  this means its energy is concentrated into a very
  s _ _ _ _ spot.

colours
one
spread
small
4
Practical Uses of Lasers

• Lasers are used to send information between
  businesses over the length of the country because
  they carry a large amount of information at high
  s _ _ _ _ .

speed
5
Practical Uses of Lasers

• Lasers are used to repair damage to the r _ _
  _ _ _ at the back of the eye. A short pulse
  from the laser welds the retina back in place.
  There is no pain because the pulse lasts for such
  a s _ _ _ _ time.

retina
short
6
Practical Uses of Lasers

• Lasers are used to vaporise c _ _ _ _ _
  tissue without scarring surrounding healthy
  tissue.

cancer
7
Visibility

• An object is visible if you can s _ _ it.
• So either it sends out its own light which
  reaches your eye or it
• r _ _ _ _ _ _ _ light into your eye. An
  object which gives off its own light is called a
  source,
• eg the s _ _ or a l _ _ _ _ _ b _
  _ _ .

see
reflects
sun
light bulb.
8
Mirrors

• Mirrors can be any shape, most are flat. A flat
  mirror is often called a plane mirror.

Mirror
i angle of incidence
r angle of reflection
r
i
reflected ray
incident ray
normal
9
Mirrors

• The normal is an imaginary line at
• r _ _ _ _ angles (90) to the surface.
• It is used as the "baseline" for measuring the
• a _ _ _ _ _ of the rays.
• Experiments show that
• Angle of r _ _ _ _ _ _ _ _ _ Angle
  of incidence

right
angles
reflection
10
Optical Fibres

• Optical fibres make use of the effect
• called total internal r _ _ _ _ _ _ _ _
  _ .
• If light enters a very narrow glass f _ _ _
  _
• and reflects from the inside at large a _ _
  _ _ _
• it does not escape.
• Even if you bend the fibre this still works.
• This is what makes fibres so u _ _ _ _ _
  in medicine.

reflection
fibre
angle
useful
11
The Fibrescope

• The fibrescope is sometimes called an
• e _ _ _ _ _ _ _ _ .
• It has two separate bundles of very t _ _ _
  
• glass fibres. One bundle takes the light from
  the
• lamp down inside the patient using t _ _ _
  _
• i _ _ _ _ _ _ _ reflection. The other
  bundle
• brings the light out using total internal
  reflection so
• The d _ _ _ _ _ can see inside the
• p _ _ _ _ _ _ .

endoscope
thin
total
internal
doctor
patients
12
The Fibrescope

13
Why fibrescopes are useful

• The fibrescope is used to see inside a patient
• without s _ _ _ _ _ _ . For example, a
  patient
• can have a stomach examination of an ulcer by
• passing the fibrescope down their t _ _ _ _ _
  .
• Without the fibrescope, the patient had to
  undergo
• s _ _ _ _ _ _.
• Using the fibrescope means the patient has
  reduced
• cutting of the skin, has less d _ _ _ _ _
  to
• healthy tissue and has a sh _ _ _ _ _
  recovery time.

surgery
throat
surgery
damage
shorter
14
Lenses

• A convex (or converging) lens is f _ _ _ _
  _ in
• the middle than at the edges.
• i.e.

fatter
15
Lenses

• This type of lens makes parallel rays of light
  come
• together (or converge) to a point of focus.
• i.e.

focus
16
Lenses

• A concave (or diverging) lens is t _ _ _ _
  _ _ in
• the middle than at the edges.
• i.e.

thinner
17
Lenses

• This type of lens makes parallel rays of light
  spread
• out (or diverge).
• i.e.

18
Summary

• focus

spread
19
Long Sight

• retina

Someone who has long sight cannot read without
g _ _ _ _ _ _ . The eye is not strong
enough to bring rays from a nearby object to a
focus inside the eye and the rays form a b _ _
_ _ _ _ image on the retina.
glasses
blurred
20
Long Sight

• retina

A c _ _ _ _ _ _ _ _ _ lens is used
to correct long sight. The diverging rays from
c _ _ _ _ objects are made more parallel.
The correct lens for the patient makes the rays
form a s _ _ _ _ image on the retina.
converging
close
sharp
21
Short Sight

• retina

Someone who has short sight cannot see f _ _
a _ _ _ objects clearly without glasses.
The eye brings rays from d _ _ _ _ _ _
objects to a focus too early and the rays form a
blurred i _ _ _ _ on the retina.
far away
distant
image
22
Short Sight

• retina

A d _ _ _ _ _ _ _ _ lens is used to
correct short sight. The p _ _ _ _ _ _ _
rays from far objects are made to diverge. The
correct lens for the patient makes the rays form
a sharp image on the r _ _ _ _ _ .
diverging
parallel
retina
23
Eye Defects
A converging lens is used to correct l _ _ _
sight. A diverging lens is used to correct
s _ _ _ _ sight.
long
short
24
Intermediate 1 Physics

• Radiations

X-Rays
25
X-rays

• X-rays are i _ _ _ _ _ _ _ _ to the
  naked eye. This means that even if they enter
  your eye, you cannot detect them.
• Photographic f _ _ _ is affected by
• X-rays and can be used to detect them.  

invisible
film
26
X-rays

• When developed, the film shows d _ _ _
  patches where the X-rays have reached it.
• X-rays are dangerous because they can
• d _ _ _ _ _ living cells.

dark
damage
27
Uses of X-rays

• X-rays are used in medicine. Skin, muscle and
  bone all absorb X-rays by
• d _ _ _ _ _ _ _ _ amounts and doctors
  use this fact to examine inside the bodies of
  patients.
• The X-rays can be given l _ _ _ energy to
  examine soft tissue like the brain.

different
less
28
Uses of X-rays

• Radiographers and doctors who work with X-rays
  all day must be p _ _ _ _ _ _ _ _ when
  they are operating the X-ray machine. They use l
  _ _ _ screens to block the X-rays, they stand
  as f _ _ as possible from the machine and
  they wear special photographic film b _ _ _
  _ _ which monitor their exposure.

protected
lead
far
badges
29
Uses of X-rays

• X-rays are used in industry. Thick steel pipes
  can be made by rolling a steel plate into a
  cylinder and then welding a seam along the pipe.
  Although a weld might look perfect it can have
  small g _ _ _ that weaken it and can be
  disastrous.

gaps
30
Uses of X-rays

• X-rays are used to study the w _ _ _ to
  make sure there are no cracks. An X-ray source is
  placed outside the pipe and an X-ray detector is
  placed inside the pipe. Any cracks in the weld
  allow X-rays to p _ _ _ through and show up
  as darker areas on the detector.
•  

weld
pass
31
Using X-rays to Check for a Broken Arm

• X-rays can pass through muscle much easier than
  they can pass through b _ _ _ . During an
  arm X-ray, the X-rays pass through the arm by
  different amounts m _ _ _ for muscle and
• l _ _ _ for bone.
•  

bone
more
less
32
Using X-rays to Check for a Broken Arm

• The X-rays hit the photographic plate on the
  other side and b _ _ _ _ en it.
• The arm shows up as d _ _ _ , with lighter
  areas for the b _ _ _ .
•  

blacken
dark
bone
33
Using X-rays to Check for a Broken Arm

• A break in the bone lets X-rays
• t _ _ _ _ _ _ and shows up as a dark
  crack.

through
34
Intermediate 1 Physics

• Radiations

Gamma Rays
35
Gamma Rays

• Like X-rays, gamma rays are invisible to the
  naked e _ _ They are also dangerous as they
  can cause damage to living c _ _ _ _ or
  change how they g _ _ _ and work. They can
  pass through much t _ _ _ _ _ _ layers
  of most materials than X-rays (up to 20 cm of
  steel). This ability to damage living cells can
  be put to good use to help destroy c _ _ _
  _ _ cells, and to kill all b _ _ _ _ _
  _ _ on medical instruments and materials

eye
cells
grow
thicker
cancer
bacteria
36
Uses of Gamma Rays

• In medicine doctors often want to follow a
  particular chemical as it moves through the body
  to allow them to find anything unusual. They add
  a radioactive version of the c _ _ _ _ _
  _ _ to the body. As it moves through the body
  the radioactive chemical can be followed using a
  detector o _ _ _ _ _ _ the body.

chemical
outside
37
Uses of Gamma Rays

• We call this chemical a radioactive t _ _ _
  _ _ because we can trace its path. The
  strength of any source of gamma radiation
  decreases with t _ _ _ In this application
  d _ _ _ _ _ _ have to be very careful the
  strength does not decrease too quickly or too
  slowly.

tracer
time
doctors
38
Uses of Gamma Rays

• In industry the penetrating power of gamma rays
  is also used to t _ _ _ _ materials,
  often through pipelines. The strength of the
  source has to be very great so that the gamma
  rays get through the steel pipes and surrounding
  concrete and its strength usually has to remain
  h _ _ _ for longer as the pipelines can be
  very long.

trace
high
39
Safety

• The gamma r _ _ _ from a source spread out
  in all directions. There are t _ _ _ _
  ways of reducing the amount of radiation you
  absorb.
• 1. Stand as f _ _ a _ _ _ from a
  source as you can.
• 2. Spend as l _ _ _ _ _ time working
  with the source as possible
• 3. Put a thick l _ _ _ shielding round a
  source.
• NEVER touch a source with your hands and
• NEVER point it in the direction of someone.

rays
three
far away
little
lead
40
Radioactive Surroundings Background Radiation

• Whether we like it or not we are all e _ _ _
  _ _ _ to radiation called background
  radiation
• 50 is from radon and thoron gases in
• our h _ _ _ _ _
• 10 from our f _ _ _ , drink and
  breathing
• 10 from Outer S _ _ _ _

exposed
houses
food
Space
41
Intermediate 1 Physics

• Radiations

Infrared and Ultraviolet
42
Infrared (IR)

• Like X-rays infrared (IR) rays are i _ _ _
  _ _ _ _ _ to the naked eye.
• Infrared is not the glow you see from a red hot
  object, that is red light.
• You can f _ _ _ infrared radiation with
  your skin.

invisible
feel
43
Infrared (IR)

• Infrared radiation is sometimes called h _ _
  _ radiation. Special cameras called thermal
  imagers, which can detect infrared, are used to
  help find people in the d _ _ _ or in
• s _ _ _ _ filled rooms.

heat
dark
smoke
44
Uses of Infrared

• In medicine, heat p _ _ _ _ _ _ _ _ _
  _ called thermograms are used to show up small
  temperature differences in the body. The
  different temperatures appear as different c _
  _ _ _ _ _ in the thermogram. Colder areas
  often mean poor b _ _ _ _
  supply while warmer areas are often the sign of a
  site of infection.

photographs.
colours
blood
45
Uses of Infrared

• In industry IR is used to d _ _ things eg.
  biscuits, glues, paint on newly
• s _ _ _ _ _ _ cars.

dry
sprayed
46
Ultraviolet (UV)

• Ultraviolet radiation (UV) cannot be detected by
  our
• e _ _ _ . It is invisible.

eyes
47
Ultraviolet radiation in medicine

• Ultraviolet radiation is used to help treat s
  _ _ _ conditions. Psoriasis is a severe form
  of rash which can be treated by chemicals which
  can harm healthy skin. Ultraviolet radiation
  shone over the affected areas switches on this c
  _ _ _ _ _ _ _ only where it is needed.

skin
chemical
48
Fluorescence

• Some chemicals g _ _ _ and emit visible
  light when they absorb UV. This is used in
• shops to test c _ _ _ _ _ c _ _ _
  _ and banknotes as they have codes marked on
  them that cannot be seen in normal light but glow
  under a _ _ lamp.

glow
credit cards
UV
49
Fluorescence

• Industry puts fluorescent plastic food s _ _
  _ _ on some products to allow automatic checks
  for tampering.
• Soap powders also fluoresce. This is to make your
  clothes appear very b _ _ _ _ _ and
  clean in sunlight (because sunlight contains _
  _ ).
•  

seals
bright
UV
50
Overexposure (to UV)

• When the skin is exposed to UV, it becomes
• t _ _ _ _ _ (suntan). If you spend too
  long in the sun or exposed to UV, your skin b
  _ _ _ _ (sunburn).
• If you keep on exposing your skin to UV over
  several months, you may develop
• s _ _ _ c _ _ _ _ _ .

tanned
burns
skin
cancer.
51
Overexposure (to UV)

• When going to countries where there is a lot of
  strong sunshine, many people use c _ _ _ _ _
  which reduce the amount of UV reaching the
  skin. These creams are
• given a "factor" number, the h _ _ _ _ _
  the factor, the less the UV exposure.

creams
higher
52
Overexposure (to UV)

• As the ozone layer gets thinner, m _ _ _
  UV reaches the Earth's surface. At the moment,
  people in Australia have to be very careful with
• overexposure to UV since they get lots of
  sunshine and the ozone layer above them is
  damaged.

more
53
Overexposure (to UV)

• Although the ozone layer above Britain is thin,
  the c _ _ _ _ cover keeps the UV down. Even
  so, people should use sun creams on
• s _ _ _ _ days.

cloud
sunny
54
Intermediate 1 Physics

• Radiations

End of Unit