scientist, discoveries & inventions MCQ section 4 Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (c)

Answer: (d)

X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV.

They are shorter in wavelength than UV rays and longer than gamma rays.

In many languages, X-radiation is called Röntgen radiation, after Wilhelm Röntgen, who is usually credited as its discoverer, and who had named it X-radiation to signify an unknown type of radiation.

Answer: (a)

In physics, cryogenics is the study of the production and behaviour of materials at very low temperatures.

It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume it starts at or below - 150°C (123 K; -238 °F).

Answer: (c)

A crescograph is a device for measuring growth in plants. It was invented in the early 20th century by Sir Jagadish Chandra Bose - an Indian polymath, physicist, biologist, botanist, and archaeologist.

Answer: (a)

Martin Cooper, an American engineer, conceived the first handheld mobile phone while at Motorola in 1973. He led the team that developed it and brought it to market in 1983. He is considered the “father of the cell phone” and is also cited as the first person in history to make a handheld cellular phone call in public.