Q: 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:
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.
The experiment was very complicated
It was a difficult theory
Electrons had even not been discovered then
Electromagnetism was not understood then
A: 3
Q: What is the antiparticle of a proton?
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).
Anti-proton
Positron
Positronium
Electron
A: 1
Q: What is positronium? It is like Hydrogen molecule but with a difference:
It is a short-lived atom like hydrogen with one electron, but with a positron instead of the proton.
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
A: 2
Q: 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 resist oxidation and have filled d orbitals, which makes them disinclined to react with other elements.
They are rare
They are highly priced
They resist oxidation
They are white in colour
A: 3
Q: The atom consists of electrons, protons and neutrons. What are protons and neutrons made of?
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.
They are indivisible
Quarks
Quarks and gluons
Quarks gluons and neutrinos
A: 3
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