Gobi Desert

The Gobi is Asia's largest desert. It is notable in the history of the Mongol Empire, the largest contiguous land empire in history. Many fossils have been found in the Gobi desert.

Acacia Trees

Acacia is a species of tree found in many parts of the world including Australia. Africa and South America. Subspecies include silver wattle and Sydney golden wattle.

How do Solar Cells Work? (Think Photons and Electrons)

A photovoltaic system uses solar panels to supply usable electric power.

Solar panels make use of the PHOTOVOLTAIC effect whereby photons from the sun hit the semiconducting material and liberate electrons.

Carrier generation and recombination knowledge is needed to understand properly how solar cells work. This is part of solid state physics, the largest branch of condensed matter physics.

Note: the photovoltaic effect is closely related to the photoelectric effect, whereby electrons are emitted when light is shone on a material. According to the "classical electromagnetic theory" this is due to the transfer of energy from the light to an electron.

Modern Frigates

A modern frigate is a ship that protects other ships, including military and merchant marine vessels. Anti-submarine escort vessels are included in the category of "frigate". The La Fayette class built by DCNS is a popular class of frigate used in the French Navy ("Marine Nationale") and those of other nations too.

When NOT to use Yours Sincerely

Yours faithfully and yours truly are the British and American equivalents used when signing off a letter to a recipient whose name you do not know.

Yours sincerely or Sincerely yours are used when you DO know the name of the recipient.

Mary Poppins' The Perfect Nanny is an example of how NOT to use Yours sincerely:

"Hurry nanny, Many thanks
Sincerely, Jane and Michael Banks".

Halogens and Diatomic Molecules in Swimming Pools

The halogens are a group in the periodic table consisting of the five related elements of fluorine, chlorine, bromine, iodine and astatine. It's also known as Group 7.

Group 1 elements react with Group 7 elements to form, for example, lithium bromide.

Halogens all exist as diatomic molecules, so Chlorine exists as Cl2, Fluorine similarly, two halogen atoms joined by a covalent bond (where electrons are shared between atoms).

 

Who was Alaric?

Alaric was the first King of the Visigoths, who emerged from the Gothic tribes, famous for his sack of Rome in 410. Alaric entered Rome via the Porta Salaria, part of the Aurelian walls. There are many famous gates to the Aurelian walls including the Porta Latina, Porta San Giovanni and Porta San Sebastiano.