XI-1-2 Physical world part-2 Pradeep Kshetrapal Physics channel скачать в хорошем качестве

XI-1-2 Physical world part-2 Pradeep Kshetrapal Physics channel

Edition E Physics, Class XI Chapter : Physical world Topic: scope, forces and laws. Classroom lecture by Pradeep Kshetrapal. Language : English mixed with Hindi. NOTES: • The scope of Physics can be divided in to two domains; Macroscopic and Microscopic. • Macroscopic domain includes phenomena at the level of Laboratory, terrestrial and astronomical scales. • Microscopic domain I ncludes atomic, molecular and nuclear phenomena. • Recently third domain in between is also thought of with name Mesoscopic Physics. This deals with group of Hundreds of atoms • Scope of physics is very wide and exciting because it deals with objects of size as large as Universe (1025m) and as small as 10-14 m, the size of a nucleus. The excitement of Physics is experienced in many fields Like: • Live transmissions through television. • Computers with high speed and memory, • Use of Robots, • Lasers and their applications Conservation Laws • In any physical phenomenon governed by different forces, several quantities do not change with time. These special quantities are conserved quantities of nature. 1.For motion under conservative force, the total mechanical Energy of a body is constant. 2.Total energy of a system is conserved, and it is valid across all domains of nature from microscopic to macroscopic. Total energy of the universe is believed to be constant. 3.Conservation of Mass was considered another conservation law, till advent of Einstein. Then it was converted to law of conservation of mass plus energy. Because mass is converted into energy and vice-versa according to equation E = mc2 The examples are annihilation and pair production. 4.Momentum is another quantity which is preserved. Similar is angular momentum of an isolated system. 5.Conservation of Electric charge is a fundamental law of nature. 6. Later there was development of law of conservation of attributes called baryon number, lepton number and so on. The laws of nature do not change with change of space and time. This is known as symmetry of space and time. This and some other symmetries play a central role in modern physics. Conservation laws are connected to this.