Questions

Electronic Flash differs from the consumable bulb flash in important aspects. Instead of creating light by burning up in an atmosphere containing oxygen, a consumable material (each bulb being used therefore only once), it produces a brilliant incandescent by discharging a current for a brief instant through a rarified gas, usually xenon. The gas glows every time the discharge is made through it but it is not consumed, so that many thousands of flashes are obtainable from a single tube, which helps to offset the much higher cost of the initial apparatus.

Cast iron is a group of iron-carbon alloys with a carbon content greater than 2% and is a brittle material.

Its usefulness derives from its relatively low melting temperature.

Phosphorescence is a phenomenon associated with an algal division called euglenophytes. 

Phosphorescence is a phenomenon when an object is capable of releasing photons of light at a longer wavelength in response to absorbing light of a shorter wavelength. The object releasing the light only releases the light after some time has passed since it absorbed the light of a short wavelength.

Euglenophytes are single-celled plant-like protists that have no cell wall.

The ancient goal of astrology was to predict human events.

"The reason for playing softly" is not a motive. Motives are the building blocks for large forms composed during the common practice period and, for some, beyond. Composers who used motives would include Beethoven, Mozart, Schubert, Mendelssohn and Brahms.

The amount of money you’ll get for a given amount of your country’s currency is based on internationally determined exchange rates. Exchange rates can be either fixed or floating. Fixed exchange rates use a standard, such as gold or another precious metal, and each unit of currency corresponds to a fixed quantity of that standard that should (theoretically) exist.