Electric current can be generated by rotating an armature loop in a magnetic field.
Chlorophyll is a photosensitive green pigment found in plants; it absorbs light energy, thus plays a vital role in photosynthesis.
The water supply system provides clean and safe drinking water for the consumers.
The United States entered World War II after the devastating attack by the Japanese navy.
This animation demonstrates different types of soil.
The archaeopteryx shows characteristics of both birds and reptiles. It is probably the ancestor of birds.
The bell is a percussion instrument and an idiophone. Many types of bells exist.
Before the American Civil war the use of slaves on plantations was typical in the Southern states.
As opposed to opencast mines, in underground mines the layers covering coal are not removed, coal is extracted from mine shafts.
Industrial estates provide infrastructure and services for companies.
Oases are areas in deserts where water is available.
Cyclones are large areas of circulating air with clouds and precipitation being formed in its centre.
Cold and warm fronts are formed where bodies of cold and warm air meet.
Groundwater and aquifers are types of underground waters.
A periodic climate pattern that occurs across the tropical Pacific Ocean every five years.
The Crow are Native Americans who inhabited the Yellowstone River valley.
An extinct group of Cephalopoda, with solid external skeletons. They are excellent index fossils.
A mammal with features typical of reptiles: it lays eggs and has a cloaca.
The piano is one of the most popular instruments in the world. It is a chordophone which produces sounds mechanically.
A spacecraft on its path is in a constant state of free fall.