Page 294 - Inventions - A Visual Encyclopedia (DK - Smithsonian)

Glossary

Air resistance A force that pushes against Atom The smallest part of a chemical Bronze Age A historical period, between
an object that is moving through the air, element, made up of particles called the Stone Age and Iron Age, that is
slowing it down. This is also called drag. protons, neutrons, and electrons. defined by the use of bronze as the most
important material for making weapons
Alloy A mixture of two or more metals. Bacteria (singular: bacterium) and tools. It began around 3000 bce
These are tiny, single-celled organisms. in the Middle East and spread around
Alternating current (AC) An electrical Some bacteria cause disease, while others the world over about 2,500 years.
GLOSSARY many times every second to allow the Battery A portable container of chemicals that comes in a variety of forms, from
help and protect the human body.
current that changes its direction of flow
Carbon An important chemical element
efficient use of electricity.
coal to diamonds. Carbon can also be
that stores and supplies electricity to
Altitude The height of an object relative
to produce millions of different
to sea or ground level. a range of devices, from toys to cars. combined with itself and other elements
Bellows A device that expands to draw compounds, from plastics to DNA.
Ammonia A colorless gas made up of in air through a valve, then contracts
nitrogen and hydrogen. It is often used to force the air through a tube. Cathode The negatively charged electrode
to make fertilizers that aid plant growth. in a cell, such as a battery.
Bipedal A human, animal, or something
Anesthetic A pain-relieving drug or else—for example, a robot—that uses Celestial A way of describing an object
gas given to a patient before a surgical two legs for walking. or event that occurs in the sky or outer
operation. It can be “local,” which affects space, such as a comet or an eclipse.
just one part of the body, or “general,” Bitumen This sticky, black substance
so the person is made temporarily made from tar or gasoline is used mainly Charcoal This gray-black porous solid,
unconscious before a major operation. to surface roads. made by heating wood in the absence of
oxygen, is mostly carbon. It has several
Ancestor A relative—usually one more Bronze A yellow-brown metal alloy uses, such as burning to generate heat
remote than a grandparent—from whom made up mostly of copper and tin. for warmth or to cook. It can also be
a human is descended. An ancestor can It is a popular choice of material used as a material for drawing.
also refer to animals and plants. for sculptures because it is strong,
hard-wearing, and rust-resistant. Circuit A complete and closed path
Anode The positively charged electrode that electricity flows around. All electric
in a cell, such as a battery. and electronic things have circuits
inside them.
Antenna This device is used to transmit
or receive radio or television signals. It is Combustion A chemical reaction in
also known as an aerial. which a fuel, such as wood or coal,
burns with oxygen from the air to
Antibiotic A medicine that kills— release heat energy.
or limits the spread of—bacterial
infections in the human body or Conductor A substance that lets heat
other animals. or electricity flow easily through it.

Antiseptic A substance that is put Contamination The process of polluting
on cuts to prevent an infection. or poisoning—for example, an oil spill
polluting the ocean, or harmful bacteria
Archaeology The study of things that poisoning the human body.
show how people lived before there
were written records. Coolant A substance, usually a liquid,
used to reduce the temperature of
Astronomy The study of objects something, such as a car engine
in space, including planets, stars, ▲ MID-19TH CENTURY CHINESE or factory machine.
and galaxies. OCEAN COMPASS

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