Satellite types

Satellites orbiting the Earth can be used for civilian or military purposes.

Non-orientable surfaces

The Möbius strip and the Klein bottle are special two-dimensional surfaces with only one side.

Conic sections

The conic section is a plane curve that is created when a right circular cone is intersected by a plane.

Meteorological instruments

This animation demonstrates instruments used to examine atmospheric phenomena.

Tidal power station

Tidal power stations utilise the daily fluctuation of the water level for producing electricity.

Cube of cubes

An exercise about the regular hexahedron built from unit cubes to help deepen your knowledge of cubes.

Thermal power station (hydrocarbon fuel)

Thermal power stations convert energy released during the combustion of fossil fuels or renewable resources into electricity.

El Niño

A periodic climate pattern that occurs across the tropical Pacific Ocean every five years.


A sphere is the set of points which are all within the same distance from a given point in space.

حاکم آزتک (قرن ۱۵)

امپراتوری آزتک یک کشور استبدادی، نظامی گرا بود که تحت فرمانروای حاكم قرار داشت۔

Submarine operation

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

Thermal expansion of bridges

The length of the metal frameworks of bridges change when the temperature changes.

Attack of Pearl Harbor (1941)

The United States entered World War II after the devastating attack by the Japanese navy.

امپراتور چینی قرون وسطایی

امپراتور امپراطوری پهناور دور و شرقی ارباب زندگی و مرگ بود۔

Geothermal power station

Geothermal power stations convert energy of hot, high-pressure water found in deeper layers of the Earth into electricity.

Thyroid gland

An important endocrine gland producing hormones that affect metabolism and the calcium balance of the body.

Cylindrical solids

This animation demonstrates various types of cylindrical solids as well as their lateral surfaces.

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