Write-Ups for Various Experiments

Below are excerpts from the spring semester lab manual for the following experiments:


Noise Measurement (Spring 08)

bulletUsing an amplifier and filters, the Johnson noise from ordinary carbon resistors is measured. From that result the Boltzman constant, k, is obtained.  From the fluctuations in the current from an LED transmitter and a Phototransistor receiver, Shot Noise is measured and a value for the charge of an electron is calculated. 



Measurement of g and Drag Forces on Falling Balls (Spring 08)

bulletIdentical sized Steel and nylon balls are dropped from various heights and the corresponding drop time is measured.  The two sets of data allow to correct for drag forces and the value of the local gravitational acceleration, g is obtained.



Diffraction by a Straight Edge (Spring 08)

bulletLaser light bisects the edge of a razor blade and produces a diffraction pattern.   The pattern is scanned by a photo tube whose position is controlled by a worm gear and a stepper motor.  From the analysis of the pattern, the wavelength of the laser light is calculated.



Measurement of the Verdent Constant of Water (Spring 08)

bulletA glass tube filled with distilled water is exposed to the magnetic field of a solenoid.  The rotation (due to the Faraday Effect) of the polarized light traversing it is measured using an optical bridge technique and a  a Lock-in amplifier.  The relation ship between the small changes in rotation angle and the applied B-field strength yields the Verdet Constant for water.