Showing posts with label Long Question. Show all posts
Showing posts with label Long Question. Show all posts

Jul 24, 2012

Hooke's Law and Its Experimental Verification

Robert Hooke performed an experiment on coiled spring, metallic rod or metallic wires etc and gave a law known as Hooke's law. It states that, "The restoring force developed on a body is directly proportional to the elongation produced on it, within the elastic limit."
      i.e. F∝x
      ∴F=-Kx       [Where K is proportionality constant.]

Young modified Hooke's statement and stated as, "Within elastic limit, the stress developed on the body is directly proportional to the strain produced on it."

Jul 23, 2012

Millikan's Oil Drop Experiment

When a spherical charged body of radius r falls under the effect of various forces in a viscous medium of viscocity η, it attends the terminal velocity vt when the viscous force becomes 6πηrvt (Stoke’s law)

Experimental setup and Theory: An experimental setup of Millikan’s experiment to determine the change in oil drop is shown in figure. At first, clock oil (non volatile) is allowed to fall drop wise from the opening of upper plate A with the help of atomizer. This law undergoes collision with air particles and gets charged. The whole apparatus is kept inside double walled chamber inside which water is circulated for cooling purpose. The chamber consists of 2 windows.

Jul 17, 2012

Huygen's Principle

Huygen’s Principle is a geometrical construction which was designed to determine the position, shape and the size of a wavefront in future if its present position and nature is known.
In 1678, Huygens proposed that every point to which a luminous disturbance reaches becomes a source of a spherical wave; the sum of these secondary waves determines the form of the wave at any subsequent time. He assumed that the secondary waves travelled only in the "forward" direction and it is not explained in the theory why this is the case. He was able to provide a qualitative explanation of linear and spherical wave propagation, and to derive the laws of reflection and refraction using this principle, but could not explain the deviations from rectilinear propagation which occur when light encounters edges, apertures and screens, commonly known as diffraction effects.  Wikipedia

Jul 11, 2012

Valence Shell Electron Pair Repulsion Theory

This is a theory to predict the shapes of molecules. It was given by Sidwick and Powel in 1940. VSEPR theory stands for Valence Shell Electron Pair Repulsion theory. This theory is based on the idea that electron pairs try to be as far apart as possible to minimize the repulsion. The main assumptions of VSEPR theory are as follows: