SCIENCE MATERIALS AND EQUIPMENTS INSIDE THE PRESCHOOL CLASSROOM

ECED 7 | Science, Health and Nature Study
1
Merylou M. Castellvi Prof. Josseme Tendido-Castro
BEEd 3A
SCIENCE MATERIALS AND EQUIPMENTS INSIDE THE PRESCHOOL
CLASSROOM
Objectives:
At the end of the lesson, the student will be able to:
Introduce different materials and equipments inside the preschool classroom
Demonstrate the different uses of science equipments
Subject Matter:
Topic: Science Materials and Equipments inside the Preschool Classroom
Reference: Wikipedia.com
Materials: visual aids, handouts, science materials
Lesson Content:
1. Balloons
A balloon is a flexible bag which can be inflated with a gas, such
as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons are made from materials
such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made
of dried animal bladders, such as the pig bladder. Some balloons are used for decorative
purposes, while others are used for practical purposes such as meteorology, medical
treatment, military defense, or transportation. A balloon's properties, including its
low density and low cost, have led to a wide range of applications.
The rubber balloon was invented by Michael Faraday in 1824, during the course of
experiments with various gases.
Party balloons are mostly made of a natural latex tapped from rubber trees, and can be
filled with air, helium, water, or any other suitable liquid or gas. The rubber's elasticity makes
the volume adjustable. As shown in the photo to the right, they can come in different colors like
the rainbow such as red, orange, yellow, green, blue, purple, etc.
Filling the balloon with air can be done with the mouth, a manual or electric inflater (such as a
hand pump), or with a source of compressed gas.
When rubber or plastic balloons are filled with helium so that they float, they typically retain
their buoyancy for only a day or so, sometimes longer. The enclosed helium atoms escape

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through small pores in the latex which are larger than the helium atoms. Balloons filled with air
usually hold their size and shape much longer, sometimes for up to a week.
Even a perfect rubber balloon eventually loses gas to the outside. The process by which a
substance or solute migrates from a region of high concentration, through a barrier or membrane,
to a region of lower concentration is called diffusion. The inside of balloons can be treated with a
special gel (for instance, the polymer solution sold under the "Hi Float" brand) which coats the
inside of the balloon to reduce the helium leakage, thus increasing float time to a week or longer.
Beginning in the late 1970s, some more expensive (and longer-lasting) foil balloons
made of thin, unstretchable, less permeablemetallised films such as Mylar (BoPET) started being
produced. These balloons have attractive shiny reflective surfaces and are often printed with
color pictures and patterns for gifts and parties. The most important attribute of metalized nylon
for balloons is its light weight, increasing buoyancy and its ability to keep the helium gas from
escaping for several weeks. Foil balloons have been criticized for interfering with power lines
Balloon modeling and balloons in art
Balloon artists are entertainers who twist and tie inflated tubular balloons into sculptures
(see balloon modeling). The balloons used for sculpture are made of extra-stretchy rubber so that
they can be twisted and tied without bursting. Since the pressure required inflating a balloon
is inversely proportional to the diameter of the balloon these tiny tubular balloons are extremely
hard to inflate initially. A pump is usually used to inflate these balloons.
Decorators may use helium balloons to create balloon sculptures. Usually the round shape of the
balloon restricts these to simple arches or walls, but on occasion more ambitious "sculptures"
have been attempted. It is also common to use balloons as table decorations for celebratory
events. Balloons can sometimes be modeled to form shapes of animals. Table decorations
normally appear with three or five balloons on each bouquet. Ribbon is curled and added with a
weight to keep the balloons from floating away.
Balloon drops and releases
A decorative use for balloons is in balloon drops. In a balloon drop, a plastic bag or net filled
with air-inflated balloons is suspended from a fixed height. Once released, the balloons fall onto
their target area below. Balloon drops are commonly performed at New Year's Eve celebrations
and at political rallies and conventions, but may also be performed at celebrations, including
graduations and weddings.

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For decades, people have also celebrated with balloon releases. This practice has been
discouraged by the balloon industry, as it has posed problematic for the environment and cities.
In recent years, legislation, such as the California Balloon Law, has been enacted to enforce
consumers and retailers to tether helium-filled foil (BoPET) balloons with a balloon weight. This
ensures that the helium-filled balloons do not float into the atmosphere, which is both potentially
injurious to animals, the environment, and power lines. Many states now have banned balloon
releases, and organizations such as Balloons Blow have been created to educate people about the
environmental issues
At many events, the balloons may contain prizes, and party-goers can pop the balloons to
retrieve the items inside.
Balloon publicity
Balloons are used for publicity at major events. Screen printing processes can be used to print
designs and company logos onto the balloons. In January 2008, the Jewish Community Relations
Council of New York organized a display of 4,200 red balloons outside the United Nations
Headquarters
Also in the 1950s at the start of the Cold War, activists in Western Europe uses balloons for
propaganda purposes that would float east over Eastern Europe, which would release newspapers
and pamphlets. Today, South Korean activists are using the same balloon method to get
information to those in North Korea.
Water balloons
Water balloons are thin, small rubber balloons filled with a liquid, usually water, instead of a gas,
and intended to be easily broken. They are usually used by children, who throw them at each
other, trying to get each other wet, as a game, competition, or practical joke. By forcing water
out the open end of a water balloon, it is possible to use it as a makeshift water gun.
Balloon rockets
Balloons are often deliberately released, creating a so-called balloon rocket or rocket balloon.
Rocket balloons work because the elastic balloons contract on the air within them, and so when
the mouth of the balloon is left open, the gas within the balloon shoots out, and, due to Newton's
third law of motion, the balloon is propelled forward. This is the same way that a rocket works.

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Flying machines
Large balloons filled with hot air or buoyant gas (often hydrogen or helium) have been
used as flying machines since the 18th century. The earliest flights were made with hot air
balloons using air heated with a flame, or hydrogen; later, helium was used. Unlike an airship, a
balloon travels with the wind.
Medicine
Angioplasty is a surgical procedure in which very small balloons are inserted into
blocked or partially blocked blood vessels near the heart. Once in place, the balloon is inflated to
clear or compress arterial plaque, and to stretch the walls of the vessel, thus preventing
myocardial. A small stent can be inserted at the angioplasty site to keep the vessel open after the
balloon's removal.
Balloon catheters are catheters that have balloons at their tip to keep them from slipping
out. For example, the balloon of a Foley catheter is inflated when the catheter is inserted into the
urinary bladder and secures its position.
Insertion of balloons subsequently filled with air or liquid can be used to stop bleeding in
hollow internal organs such as stomach or uterus.
Air pressure
Once inflated with regular, atmospheric air, the air inside the balloon will have a greater
air pressure than the original atmospheric air pressure.
Air pressure, technically, is a measurement of the amount of collisions against a surface
at any time. In the case of balloon, it's supposed to measure how many particles at any in any
given time space collide with the wall of the balloon and bounce off. However, since this is near
impossible to measure, air pressure seems to be easier described as density. The similarity comes
from the idea that when there are more molecules in the same space, more of them will be
heading towards a collision course with the wall.
The first concept of air pressure within a balloon that is necessary to know is that air
pressures "try" to even out. With all the bouncing against the balloon wall (both interior and
exterior) there will be a certain amount of expansion/contraction. As air pressure itself is a
description of the total forces against an object, each of these forces, on the outside of the
balloon, causes the balloon to contract a tiny bit, while the inside forces cause the balloon to
expand. With this knowledge, one would immediately assume that a balloon with high air

5
pressure inside would expand based on the high amount of internal forces, and vice versa. This
would make the inside and outside air pressures equal.
However, balloons have a certain elasticity to them that needs to be taken into account.
The act of stretching a balloon fills it with potential energy. When it is released, the potential
energy is turned into kinetic energy and the balloon snaps back into its original position, though
perhaps a little stretched out. When a balloon is filled with air, the balloon is being stretched.
While the balloon is constantly releasing kinetic energy in an attempt to contract, it is also being
pushed back out by the constant bouncing of the internal air molecules. The internal air has to
exert force not only to counteract the external air to keep the air pressures "even", but it also has
to counteract the natural contraction of the balloon. Therefore, it requires more air pressure (or
force) than the air outside the balloon wall.
Two-balloon experiment
The two-balloon experiment is a simple experiment involving interconnected balloons.
It is used in physics classes as a demonstration of elasticity.
Two identical balloons are inflated to different diameters and connected by means of a tube. The
flow of air through the tube is controlled by a valve or clamp. The clamp is then released,
allowing air to flow between the balloons. For many starting conditions, the smaller balloon then
gets smaller and the balloon with the larger diameter inflates even more. This result is surprising,
since most people assume that the two balloons will have equal sizes after exchanging air.
The behavior of the balloons in the two-balloon experiment was first explained theoretically
by David Merritt and Fred Weinhaus in 1978.
2. Rocks
In geology, a rock is a naturally occurring solid aggregate of one or
more minerals or mineraloids. For example, the common rock, granite, is a combination of
the quartz, feldspar and biotite minerals. The Earth's outer solid layer, the lithosphere, is made of
rock.
Rocks have been used by mankind throughout history. From the Stone Age rocks have been
used for tools. The minerals and metals we find in rocks have been essential to human
civilization.

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Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The
scientific study of rocks is called petrology, which is an essential component of geology.
Classification of Rocks
At a granular level, rocks are composed of grains of minerals, which, in turn,
are homogeneous solids formed from a chemical compoundthat is arranged in an orderly manner.
The aggregate minerals forming the rock are held together by chemical bonds. The types and
abundance of minerals in a rock are determined by the manner in which the rock was formed.
Many rocks contain silica (SiO2); a compound of silicon and oxygen that forms 74.3% of the
Earth's crust. This material forms crystals with other compounds in the rock. The proportion of
silica in rocks and minerals is a major factor in determining their name and properties
Rocks are geologically classified according to characteristics such as mineral and chemical
composition, permeability, the texture of the constituent particles, and particle size. These
physical properties are the end result of the processes that formed the rocks. Over the course of
time, rocks can transform from one type into another, as described by the geological model
called the rock cycle. These events produce three general classes of rock: igneous, sedimentary,
and metamorphic.
The three classes of rocks are subdivided into many groups. However, there are no hard and
fast boundaries between allied rocks. By increase or decrease in the proportions of their
constituent minerals they pass by every gradation into one another, the distinctive structures also
of one kind of rock may often be traced gradually merging into those of another. Hence the
definitions adopted in establishing rock nomenclature merely correspond to more or less
arbitrary selected points in a continuously graduated series.
a. Igneous rocks
Igneous rock (derived from the Latin word igneus meaning of fire, from ignis meaning
fire) forms through the cooling and solidification ofmagma or lava. This magma can be
derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically,
the melting of rocks is caused by one or more of three processes: an increase in temperature,
a decrease in pressure, or a change in composition.
Igneous rocks are divided into two main categories: plutonic
rock and volcanic. Plutonic or intrusive rocks result when magma cools
andcrystallizes slowly within the Earth's crust. A common example of this type is granite.

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Volcanic or extrusive rocks result from magma reaching the surface either
as lava or fragmental ejecta, forming minerals such as pumice or basalt. The chemical
abundance and the rate of cooling of magma typically forms a sequence known as Bowen's
reaction series, after the Canadian petrologist Norman L. Bowen. Most major igneous rocks
are found along this scale.
About 64.7% of the Earth's crust by volume consists of igneous rocks; making it the most
plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, and
17% granodiorites and diorites. Only 0.6% are syenites and 0.3% peridotites and dunites.
The oceanic crust is 99% basalt, which is an igneous rock of mafic composition. Granites
and similar rocks, known as meta-granitoids, form much of the continental crust. Over 700
types of igneous rocks have been described, most of them having formed beneath the surface
of Earth's crust. These have diverse properties, depending on their composition and how they
were formed.
b. Sedimentary rocks
Sedimentary rocks are formed by sedimentation of particles at or near the Earth's surface
and within bodies of water. This process causes clastic sediments or organic particles
(detritus) to settle and accumulate, or for minerals to chemically precipitate (evaporite) from
a solution. The particulate matter then undergoes compaction and cementation
during diagenesis.
Before being deposited, sediment was formed by weathering and erosion in a source area,
and then transported to the place of deposition by water, wind, ice, mass
movement or glaciers which are called agents of denudation. Mud rocks comprise 65%
(mudstone,shale and siltstone); sandstones 20 to 25% and carbonate rocks 10 to 15%
(limestone and dolostone).[3]
About 7.9% of the crust by volume is composed of sedimentary
rocks, with 82% of those being shales, while the remainder consists of limestone (6%),
sandstone and arkoses (12%).
c. Metamorphic rocks
Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous
rock or another older metamorphic rock—to different temperature and pressure conditions
than those in which the original rock was formed. This process is called metamorphism;
meaning to "change in form". The result is a profound change in physical properties and
chemistry of the stone. The original rock, known as the protolith, transforms into other

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mineral types or else into other forms of the same minerals, such as by recrystallization. The
temperatures and pressures required for this process are always higher than those found at
the Earth's surface: temperatures greater than 150 to 200 °C and pressures of
1500 bars. Metamorphic rocks compose 27.4% of the crust by volume.
The three major classes of metamorphic rock are based upon the formation mechanism.
An intrusion of magma that heats the surrounding rock causes contact metamorphism—a
temperature-dominated transformation. Pressure metamorphism occurs when sediments are
buried deep under the ground; pressure is dominant and temperature plays a smaller role.
This is termed burial metamorphism, and it can result in rocks such as jade. Where both heat
and pressure play a role, the mechanism is termed regional metamorphism. This is typically
found in mountain-building regions.
Depending on the structure, metamorphic rocks are divided into two general categories.
Those that possess a texture are referred to as foliated; the remainder are termed non-foliated.
The name of the rock is then determined based on the types of minerals present. Schist are
foliated rocks that are primarily composed of lamellar minerals such as micas. A gneiss has
visible bands of differing lightness, with a common example being the granite gneiss. Other
varieties of foliated rock include slates, phyllites, and mylonite. Familiar examples of non-
foliated metamorphic rocks include marble, soapstone, and serpentine. This branch
contains quartzite—a metamorphosed form of sandstone—and hornfels.
The use of rocks has had a huge impact on the cultural and technological development of
the human race. Rocks have been used by humans and other hominids for more
than 2 million years. Lithic technology marks some of the oldest and continuously used
technologies. The mining of rocks for their metal ore content has been one of the most
important factors of human advancement, which has progressed at different rates in different
places in part because of the kind of metals available from the rocks of a region.
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth,
from an ore body, vein or (coal) seam. This term also includes the removal of soil. Materials
recovered by mining include base metals, precious
metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash. Mining is
required to obtain any material that cannot be grown through agricultural processes, or
created artificially in a laboratory or factory. Mining in a wider sense comprises extraction of
any non-renewable resource (e.g.,petroleum, natural gas, or even water).

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Mining of stone and metal has been done since pre-historic times. Modern mining processes
involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction
of the desired materials and finally reclamation of the land to prepare it for other uses once the
mine is closed.
The nature of mining processes creates a potential negative impact on the environment both
during the mining operations and for years after the mine is closed. This impact has led to most
of the world's nations adopting regulations to moderate the negative effects of mining operations.
Safety has long been a concern as well, though modern practices have improved safety in mines
significantly.
3. Mirrors
A mirror is an object that reflects light in a way that preserves much of its original quality
subsequent to its contact with the mirror.
Some mirrors also filter out some wavelengths, while preserving other wavelengths in the
reflection. This is different from other light-reflecting objects that do not preserve much of the
original wave signal other than color and diffuse reflected light. The most familiar type of mirror
is the plane mirror, which has a flat surface. Curved mirrors are also used, to produce
magnified or diminished images or focus light or simply distort the reflected image.
Mirrors are commonly used for personal grooming or admiring oneself (in which case
the archaic term looking-glass is sometimes still used), decoration, and architecture. Mirrors are
also used in scientific apparatus such as telescopes and lasers, cameras, and industrial machinery.
Most mirrors are designed for visible light; however, mirrors designed for other types of waves
or other wavelengths of electromagnetic radiation are also used, especially in non-
optical instruments.
History
The first mirrors used by people were most likely pools of dark, still water, or water collected in
a primitive vessel of some sort. The earliest manufactured mirrors were pieces of polished stone
such as obsidian, a naturally occurring volcanic glass. Examples of obsidian mirrors found
in Anatolia (modern-day Turkey) have been dated to around 6000 BC. Polished stone mirrors
from Central and South America date from around 2000 BC onwards. Mirrors of polished copper
were crafted in Mesopotamia from 4000 BC, and in ancient Egypt from around 3000 BC. In
China, bronze mirrors were manufactured from around 2000 BC, some of the earliest bronze and
copper examples being produced by the Qijia culture. Mirrors made of other metal mixtures
(alloys) such as copper and tin speculum metal may have also been produced in China and

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India. Mirrors of speculum metal or any precious metal were hard to produce and were only
owned by the wealthy.
Metal-coated glass mirrors are said to have been invented in Sidon (modern-day Lebanon) in the
first century AD, and glass mirrors backed with gold leaf are mentioned by the Roman
author Pliny in his Natural History, written in about 77 AD. The Romans also developed a
technique for creating crude mirrors by coating blown glass with molten lead.
Parabolic mirrors were described and studied in classical antiquity by the
mathematician Diocles in his work On Burning Mirrors. Ptolemy conducted a number of
experiments with curved polished iron mirrors, and discussed plane, convex spherical and
concave spherical mirrors in his Optics. Parabolic mirrors were also described by the
physicist Ibn Sahl in the 10th century, and Ibn al-Haytham discussed concave and convex
mirrors in both cylindrical and spherical geometries, carried out a number of experiments with
mirrors, and solved the problem of finding the point on a convex mirror at which a ray coming
from one point is reflected to another point. By the 11th century, clear glass mirrors were being
produced in Moorish Spain.
In China, people began making mirrors with the use of silver-mercury amalgams as early as 500
AD.[16]
Some time during the earlyRenaissance, European manufacturers perfected a superior
method of coating glass with a tin-mercury amalgam. The exact date and location of the
discovery is unknown, but in the 16th century, Venice, a city famed for its glass-making
expertise, became a centre of mirror production using this new technique. Glass mirrors from this
period were extremely expensive luxuries. The Saint-Gobain factory, founded by royal initiative
in France, was an important manufacturer, and Bohemian and German glass, often rather
cheaper, was also important.
The invention of the silvered-glass mirror is credited to German chemist Justus von Liebig in
1835.[18]
His process involved the deposition of a thin layer of metallic silver onto glass through
the chemical reduction of silver nitrate. This silvering process was adapted for mass
manufacturing and led to the greater availability of affordable mirrors. Nowadays, mirrors are
often produced by the wet deposition of silver (or sometimes aluminum via vacuum deposition)
directly onto the glass substrate.
Types of glass mirrors
There are many types of glass mirrors, each representing a different manufacturing process and
reflection type.
An aluminium glass mirror is made of a float glass manufactured using vacuum
coating, i.e. aluminium powder is evaporated (or "sputtered") onto the exposed surface of
the glass in a vacuum chamber and then coated with two or more layers of waterproof
protective paint.

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A low aluminium glass mirror is manufactured by coating silver and two layers of
protective paint on the back surface of glass. A low aluminium glass mirror is very clear,
light transmissive, smooth, and reflects accurate natural colors. This type of glass is
widely used for framing presentations and exhibitions in which a precise color
representation of the artwork is truly essential or when the background color of the frame
is predominantly white.
A safety glass mirror is made by adhering a special protective film to the back surface
of a silver glass mirror, which prevents injuries in case the mirror is broken. This kind of
mirror is used for furniture, doors, glass walls, commercial shelves, or public areas.
A silkscreen printed glass mirror is produced using inorganic color ink that prints
patterns through a special screen onto glass. Various colors, patterns, and glass shapes are
available. Such a glass mirror is durable and more moisture resistant than ordinary
printed glass and can serve for over 20 years. This type of glass is widely used for
decorative purposes (e.g., on mirrors, table tops, doors, windows, kitchen chop boards,
etc.).
A silver glass mirror is an ordinary mirror, coated on its back surface with silver, which
produces images by reflection. This kind of glass mirror is produced by coating a silver,
copper film and two or more layers of waterproof paint on the back surface of float glass,
which perfectly resists acid and moisture. A silver glass mirror provides clear and actual
images, is quite durable, and is widely used for furniture, bathroom and other decorative
purposes.
Decorative glass mirrors are usually handcrafted. A variety of shades, shapes and glass thickness
are often available.
Effects
Shape of a mirror's surface
A beam of light reflects off a mirror at an angle of reflection equal to its angle of incidence (if
the size of a mirror is much larger than the wavelength of light). That is, if the beam of light is
shining on a mirror's surface at a ° angle vertically, then it reflects from the point of incidence
at a ° angle from vertically in the opposite direction. This law mathematically follows from the
interference of a plane wave on a flat boundary (of much larger size than the wavelength).
In a plane mirror, a parallel beam of light changes its direction as a whole, while still
remaining parallel; the images formed by a plane mirror are virtual images, of the same size
as the original object (see mirror image).
In a concave mirror, parallel beams of light become a convergent beam, whose rays
intersect in the focus of the mirror. Also known as converging mirror

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In a convex mirror, parallel beams become divergent, with the rays appearing to diverge
from a common point of intersection "behind" the mirror.
Spherical concave and convex mirrors do not focus parallel rays to a single point due
to spherical aberration. However, the ideal of focusing to a point is a commonly-used
approximation. Parabolic reflectors resolve this, allowing incoming parallel rays (for
example, light from a distant star) to be focused to a small spot; almost an ideal point.
Parabolic reflectors are not suitable for imaging nearby objects because the light rays are not
parallel.
Mirror image
If one looks in a mirror, one's image reverses (e.g., if one raises one's right hand, one's left hand
will appear to go up in the mirror). However, a mirror does not "swap" left and right, any more
than it swaps top and bottom. A mirror reverses the forward/backward axis, and we define left
and right relative to front and back. Flipping front/back and left/right is equivalent to a rotation
of 180 degrees about the vertical axis (in the same way that text which is back-to-
front and upside-down simply looks like it has been rotated 180 degrees on the page). Therefore,
looking at an image of oneself with the front/back axis flipped is the same as looking at an image
with the left/right axis flipped and the whole figure rotated 180 degrees about the vertical axis,
which is exactly what one sees when standing in front of a mirror.
Safety and easier viewing
Convex mirrors
Convex mirrors provide a wider field of view than flat mirrors, and are often used on
vehicles, especially large trucks, to minimize blind spots. They are sometimes placed
at road junctions, and corners of sites such as parking lots to allow people to see around
corners to avoid crashing into other vehicles or shopping carts. They are also sometimes
used as part of security systems, so that a single video camera can show more than
one angle at a time.
Mouth mirrors or "dental mirrors"
Mouth mirrors or "dental mirrors" are used by dentists to allow indirect vision and
lighting within the mouth. Their reflective surfaces may be either flat or curved. Mouth
mirrors are also commonly used by mechanics to allow vision in tight spaces and around
corners in equipment.
Rear-view mirrors
Rear-view mirrors are widely used in and on vehicles (such as automobiles, or bicycles),
to allow drivers to see other vehicles coming up behind them. Some motorcycle
helmets have a built-in so-called MROS (Multiple Reflective Optic System): a set of
reflective surfaces inside the helmet that together function as a rear-view mirror.[22]
On

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rear-view sunglasses, the left end of the left glass and the right end of the right glass work
as mirrors.
One-way mirrors and windows
One-way mirrors
One-way mirrors (also called two-way mirrors) work by overwhelming dim
transmitted light with bright reflected light. A true one-way mirror that actually allows
light to be transmitted in one direction only without requiring external energy is not
possible as it violates thesecond law of thermodynamics: if one placed a cold object on
the transmitting side and a hot one on the blocked side, radiant energy would be
transferred from the cold to the hot object. Thus, though a one-way mirror can be made to
appear to work in only one direction at a time, it's actually reflective from either side.
One-way windows
One-way windows can be made to work with polarized light in the laboratory
without violating the second law. This is an apparent paradox that stumped some great
physicists, although it does not allow a practical one-way mirror for use in the real
world. Optical isolators are one-way devices that are commonly used with lasers.
Face-to-face mirrors
Two or more mirrors placed exactly face to face can give an infinite regress of
reflections. Some devices use this to generate multiple reflections:
Fabry–Pérot interferometer
Laser (which contains an optical cavity)
3D Kaleidoscope to concentrate light[27]
momentum-enhanced solar sail
Unusual Kinds of Mirrors
Other types of reflecting device are also called "mirrors".
Acoustic mirrors are passive devices used to reflect and perhaps to focus sound
waves. Acoustic mirrors were used for selective detection of sound waves,
especially during World War II. They were used for detection of enemy aircraft
prior to the development of radar. Acoustic mirrors are used for remote probing of
the atmosphere; they can be used to form a narrow diffraction-limited beam.[
They can also be used for underwater imaging.
Active mirrors are mirrors that amplify the light they reflect. They are used to
make disk lasers.[46]
The amplification is typically over a narrow range
of wavelengths, and requires an external source of power.

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Atomic mirrors are devices which reflect matter waves. Usually, atomic mirrors
work at grazing incidence. Such mirrors can be used for
atomic interferometry and atomic holography. It has been proposed that they can
be used for non-destructive imaging systems withnanometer resolution.[47]
Cold mirrors are dielectric mirrors that reflect the entire visible light spectrum,
while efficiently transmitting infrared wavelengths. These are the converse of hot
mirrors.
Corner reflectors use three flat mirrors to reflect light back towards its source.
They are used for emergency location, and even laser ranging to the Moon.
Hot mirrors reflect infrared light while allowing visible light to pass. These can
be used to separate useful light from unneeded infrared to reduce heating of
components in an optical device. They can also be used as dichroic beamsplitters.
(Hot mirrors are the converse of cold mirrors.)
Metallic reflectors are used to reflect infrared light (such as in space
heaters or microwaves).
Non-reversing mirrors are mirrors that provide a non-reversed image of their
subjects.
X-ray mirrors produce specular reflection of X-rays. All known types work only
at angles near grazing incidence, and only a small fraction of the rays are
reflected.[48]
See also X-ray optics.

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