physics multiple choice questions modern physics

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Introduction - You have learnt in the earlier chapters that flow of electrons constitutes an electric current and current can be generated from a battery or a generator. Scientists later discovered that there are many other ways of producing the stream of electron..

Summary - When certain metals are heated to a high temperature, they emit thermions (electrons) and the phenomenon is called thermionic emission Cathode rays are a stream of negatively charged particles emitted from the cathode of an evacuated bulb, when a voltage of nearly 3000 volts given across ..

Importance of Radio Waves in Modern Communication - Radio waves are electromagnetic waves of wavelength 10 - 3 m and higher. Their frequency range is from a few kHz to nearly a few hundred MHz. The propagation of radio waves through the atmosphere is relevant in all modern forms..

Even though the laws of friction have been understood since a long time, some properties were understood properly, only after the discovery of atoms and molecules. No matter how well polished two surfaces are, at the atomic level they are never plane. Sometimes, when these extremely well polished ..

Coulomb's law describes only the interaction of two point charges. Experiments show that when two charges exert forces simultaneously on a third charge, the total force acting on that charge is the vector sum of the forces that the two charges would exert individually. This important property..

When an object is kept between two plane mirrors inclined at an angle q , more than one image forms. The total number of images formed in such a case can be related to the angle as follows :..

Multiplication of Vectors by Real Numbers, i.e., Scalar Multiple of a Vector - The multiplication of a vector by a real number assumes a lot of significance in such statements as - velocity of car B is double the velocity of car A l . When a vector is multiplied by a r..

Optics..