Book excerpt: Introduction * Torsional Pendulum * Compound Pendulum * Laser Grating Determination Of Wavelength * Optical Fibres-Measurement Of Numerical Aperture * Optical Fibres * Attenuation In Fibres * Spectrometer-Refractive Index Of Prism * Spectrometer * I-D Curve O Air Wedged * Hysterisis-Energy Loss Of Ferrites * B.H. Curve-Energy Loss Of Ferrites (Display Of B.H. Curve On Cro Screen) * Magnetic Susceptibility-Quincke'S Method * Band Gap Energy Of A Semiconductor * Semiconductor Diode Characteristics * Compressibility Of Liquid-Ultrasonic Interferometer * Excess Adiabatic Compressibility Of A Binary * Mixture-Ultrasonic Interferometer * Magnetic Susceptibility-Quincke'S Method (Alternative Approach) * Magnetic Susceptibility-Guoy'S Method.