DC motor

DC motors consist of a permanent magnet and a coil within the magnet, with electric...

Aerodynamic lift

Due to their asymmetrical profile of the wings, lift is produced while flying at a high...

Radial engine

Radial engines are used primarily in aeroplanes and helicopters.

Melting and freezing

During freezing hydrogen bonds are formed between water molecules resulting in a crystal...

Submarine operation

Submarines submerge and surface by changing the average density of the hull.

p-V-T diagram for ideal gases

The relationship between the pressure, volume and temperature of ideal gases is described...

Generating alternating current

Electric current can be generated by rotating an armature loop in a magnetic field.


Mercury is innermost and smallest planet of the Solar System.

Fuel cell

A fuel cell provides environment-friendly electric energy produced by the chemical...

Lead-acid battery

Electrochemical processes in a lead-acid battery produce electric current.


Possible traces of water and life are sought on Mars.


Neptune is the outermost planet of the Solar System, the smallest of the giant planets

Time zones

The Earth is divided into 24 time zones. Standard time is the time used within time zones.


Uranus is the 7th planet from the Sun, a gas giant.


Venus is the 2nd planet from the Sun, the brightest object on the night sky (after the Moon).

Space Shuttle

The Space Shuttle was a manned, reusable spacecraft operated by NASA.

Voyager space probes

The Voyager space probes were the first man-made objects to leave the Solar System. They...


Saturn is the second largest planet in the Solar System, easily recognisable by its rings.

Formation of hydrogen molecules

Hydrogen atoms within hydrogen molecules are held together by a covalent bond.

Milky Way

The diameter of our galaxy is about 100,000 light years; it contains more than 100...

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