Gunpowder was the first chemical explosive and the only one known until the invention of nitrocellulose, nitroglycerin, smokeless powder, and TNT in the second half of the 19th century. Prior to the invention of gunpowder, many incendiary and burning devices had been used, including Greek fire. Roger Bacon invented gunpowder.

Correct Option: A

Gunpowder was the first chemical explosive and the only one known until the invention of nitrocellulose, nitroglycerin, smokeless powder, and TNT in the second half of the 19th century. Prior to the invention of gunpowder, many incendiary and burning devices had been used, including Greek fire. Roger Bacon invented gunpowder.

In electronics, a vacuum tube, thermionic valve, tube, or valve is a device controlling electric current through a vacuum in a sealed container. The container is often thin transparent glass in a roughly cylindrical shape. Sir John Ambrose Fleming (29 November 1849 – 18 April 1945) was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, then called the kenotron in 1904. He is also famous for the left hand rule (for electric motors).

Correct Option: C

In electronics, a vacuum tube, thermionic valve, tube, or valve is a device controlling electric current through a vacuum in a sealed container. The container is often thin transparent glass in a roughly cylindrical shape. Sir John Ambrose Fleming (29 November 1849 – 18 April 1945) was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, then called the kenotron in 1904. He is also famous for the left hand rule (for electric motors).

The electron is a subatomic particle with a negative elementary electric charge. An electron has a mass that is approximately 1/1836 that of the proton. The intrinsic angular momentum (spin) of the electron is a half-integer value in units of h, which means that it is a fermion. Like all matter, they have quantum mechanical properties of both particles and waves, so they can collide with other particles and can be diffracted like light. The electron was identified as a particle in 1897 by J. J. Thomson and his team of British physicists.

Correct Option: C

The electron is a subatomic particle with a negative elementary electric charge. An electron has a mass that is approximately 1/1836 that of the proton. The intrinsic angular momentum (spin) of the electron is a half-integer value in units of h, which means that it is a fermion. Like all matter, they have quantum mechanical properties of both particles and waves, so they can collide with other particles and can be diffracted like light. The electron was identified as a particle in 1897 by J. J. Thomson and his team of British physicists.

A videotape is a recording of images and sounds on to magnetic tape as opposed to film stock used in filmmaking or random access digital media. Videotapes are also used for storing scientific or medical data, such as the data produced by an electrocardiogram. Charles P. Ginsburg invented the videotape. He worked for Ampex, and was inspired by the reel-to-reel machines used for recording sound.

Correct Option: B

A videotape is a recording of images and sounds on to magnetic tape as opposed to film stock used in filmmaking or random access digital media. Videotapes are also used for storing scientific or medical data, such as the data produced by an electrocardiogram. Charles P. Ginsburg invented the videotape. He worked for Ampex, and was inspired by the reel-to-reel machines used for recording sound.

An optical fiber (or optical fibre) is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Narinder Singh Kapany (born 31 October 1926 in Moga, Punjab, India) is an Indian born American physicist invented optical fibre.

Correct Option: B

An optical fiber (or optical fibre) is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Narinder Singh Kapany (born 31 October 1926 in Moga, Punjab, India) is an Indian born American physicist invented optical fibre.