scientist, discoveries & inventions MCQ section 3 MCQ Questions & Answers Detailed Explanation

Answer: (d)

The connection between electricity and magnetism was discovered by famous Danish chemist and physicist, Hans Christian Oersted in 1819. Starting about a decade after Oersted’s discovery, Michael Faraday demonstrated essentially the opposite of what Oersted had found–that a changing magnetic field induces an electric current.

He achieved an electrical current from a changing magnetic field, a phenomenon known as electromagnetic induction. Following Faraday’s work, James Clerk Maxwell developed equations, formally unifying electricity and magnetism.

So it was Maxwell who formulated the relationship between electricity and magnetism.

Answer: (b)

Answer: (a)

Radar is an object detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.

The radar dish or antenna transmits pulses of radio waves or microwaves which bounce off any object in their path.

In 1922 A. Hoyt Taylor and Leo C. Young, researchers working with the U.S. Navy invented Radar.

Answer: (d)

Euclid, also known as Euclid of Alexandria, was a Greek mathematician, often referred to as the “Father of Geometry”. He was active in Alexandria during the reign of Ptolemy I (323–283 BC). Euclid deduced the principles of what is now called Euclidean geometry from a small set of axioms.

Euclid also wrote works on perspective, conic sections, spherical geometry, number theory and rigour. Although many of the results in Elements originated with earlier mathematicians, one of Euclid’s accomplishments was to present them in a single, logically coherent framework, making it easy to use and easy to reference, including a system of rigorous mathematical proofs that remains the basis of mathematics 23 centuries later.

Answer: (b)

Van Leeuwenhoek discovered “protozoa” - the single-celled organisms and he called them “animalcules”. He also improved the microscope and laid the foundation for microbiology. He is often cited as the first microbiologist to study muscle fibres, bacteria, spermatozoa and blood flow in capillaries.

Although, he did not have much education or scientific background, yet he defied all odds to be reckoned as a great scientist through his skilful observations, insight and unmatched curiosity. He revolutionized biological science by exposing microscopic life to the world.

Answer: (d)

A sextant is a doubly reflecting navigation instrument used to determine the angle between an astronomical object and the horizon for the purposes of celestial navigation.

Common uses of the sextant include sighting the sun at solar noon or Polaris at night (in the Northern Hemisphere) to determine latitude.