B.Sc Mechanics

Preface

This book is to be based on the Syllabus of B.Sc(Physics main) Mechanics paper of the Calicut University ,Kerala,India.

Special Thoery of Relativity

Michelson Morley Experiment

The aim of Michelson-Morley experiment was to prove the existence of Eher bydetecting the relative motion between Earth and Ether. The Principle was that if light is to travel with differnt velocities along different directions with respect to earth,a beam of light split and send along two directions perpendicular to each other after normal reflection at the same distance,will have a path differnce and will therefore interfere giving fringes. The apparatus consists of a monochromatic source of light collimatted and madeto fall on a semi-silvered glass plate kept at 45 degrees to the incident beamand the whole apparatus so oriented that the one of the reflected beams travelsalong the direction of motion of ear45 degrees to the incident beamand the whole apparatus so oriented that the one of the reflected beams travelsalong the direction of motion of earth.Two mirrors kept at equal distance from Sreflect the light and they interfere after reflection and the interference fringes are observed through a microscope Let c be the velocity of light and v the velocity of earth through Ether.

Then velocity of light along the direction of motion of earth $=c-v$ 
velocity of light opposite to the direction of earth =c+v   
Time taken by light to go back and forth along  direction of  light =$\frac{d}{c-v}-\frac{d}{c+v}$