Sci-Five | The Hindu Science Quiz — On particles
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In 1879, American physicist Edwin Herbert Hall discovered the ‘Hall effect’ which goes by his name. It describes the behaviour of current flowing in a conductor when an perpendicular magnetic field is applied. One of the reasons his discovery was considered brilliant is the following:
- The experiment was very complicated
- It was a difficult theory
- Electrons had even not been discovered then
- Electromagnetism was not understood then
Electrons were discovered only later, in 1897, by JJ Thomson in the cathode ray tube experiments. They had been postulated earlier. Yet E.H. Hall made measurements of the tiny effects due to electrons in his experiment.
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What is the antiparticle of a proton?
- Anti-proton
- Positron
- Positronium
- Electron
Anti-proton is the anti-particle of proton. It has a mass equal to the proton, an equal spin angular momentum but negative charge (opposite of the proton).
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What is positronium? It is like Hydrogen molecule but with a difference:
- It has a proton and a neutron in its nucleus
- It has an electron and positron instead of proton
- It has a proton and two neutrons in its nucleus
- It is a positron without a positive charge
It is a short-lived atom like hydrogen with one electron, but with a positron instead of the proton.
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Noble metals are elements that do not easily react with other molecules, and the list includes gold, platinum and rhodium among others. What makes a noble metal noble?
- They are rare
- They are highly priced
- They resist oxidation
- They are white in colour
They resist oxidation and have filled d orbitals, which makes them disinclined to react with other elements.
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The atom consists of electrons, protons and neutrons. What are protons and neutrons made of?
- They are indivisible
- Quarks
- Quarks and gluons
- Quarks gluons and neutrinos
Every proton or neutron is made up of three quarks. The gluons provide the effect that holds these together. The strong force is mediated by the gluons.
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