Explore BrainMass

Phase Changes

A phase change, or transition is the transformation of thermodynamic systems from one phase or state of matter to another. A phase in a thermodynamic system and the state of matter has uniform physical properties. During a phase transition, certain properties of the medium change discontinuously. This results in come external condition such as temperature and pressure. Phase transitions are commonly observed in nature. The most commonly used transition is between solid, liquid and gaseous states of matter.

Phase transitions are classified based on the behavior of the thermodynamic free energy as a function of other thermodynamic variables.  First-order phase transition exhibits a discontinuity in the first derivative of the free energy with respect to some thermodynamic variable. Second-order phase transitions are continuous in the first derivative but exhibit discontinuity in the second derivative of free energy. This method is called the Ehrenfest’s classification. Although this classification method is useful, it is found to be inaccurate because it does not take into consideration where the derivative of free energy diverges. 

Thin film interference and air gap of variable thickness

** Please see the attached file for the complete problem description ** Say you saw the following interference pattern due to air between two glass slides: (please see the attached file) a) What can you say about the thickness of the air gap across the slide? Is it uniform? What does it mean if there isn't any color (e.g.,

Frequency is detected by the French submarine in the signal

61. A French submarine and a U.S. submarine move toward each other during maneuvers in motionless water in the North Atlantic. The French submarine moves at speed vF = 50.00 km/h, and the U.S. submarine at vUS = 67.00 km/h. The French submarine sends out a sonar signal (sound wave in water) at 1.000 x 103 Hz. Sonar waves travel

Lowest frequency that produces interference

Part 1 A microphone is located on the line connecting two speakers that are 0.524 m apart and oscillating 180° out of phase. The microphone is 1.97 m from the midpoint of the two speakers. What is the lowest frequency that produces an interference maximum at the microphone's location? Part 2 What is the next lowest fr

Interference for Sunlight Incidents

7. Sunlight incident on a screen containing two long narrow slits 0.2mm apart casts a pattern on a white sheet of paper 2m beyond. What is the distance (in mm) separating the violet (lambda = 400nm) in the first-order band from the red (lambda = 600nm) in the second order? 8. A soap film has an index of refraction of 1.334. H

Optical Waves

A ray of light travelling down an optical fibre. See attached file for full problem description.

Phase Changes in a Bubble

a.) A 1-cm3 air bubble at a depth of 419 meters and at a temperature of 4 oC rises to the surface of the lake where the temperature is 12.3 oC, to the nearest tenth of a cm3, what is its new volume? b.) How many micromoles (to 1 decimal place) of air is in the bubble?

Measurement of Physiology - Respiration Signal

A strap, instrumented to measure stretch, is worn around the chest to detect respiration whilst a subject is at-rest. The resulting signal is contaminated by electrical noise from the mains at 50 Hz with a similar amplitude to the respiration signal. Sketch what the contaminated signal might look like. The signal is then sample

Interference of light: thickness of the layer

A layer of transparent plastic (n = 1.59) on glass (n = 1.52) looks dark when viewed in reflected light whose wavelength is 570 nm in vacuum. Find the two smallest possible nonzero values for the thickness of the layer. answer in nanometers

Light reflected from air wedge formed by glass plates.

I am having a bit of trouble with a problem in a algebra based physics course. When blue light (wavelength 589nm)is reflected from an air wedge formed by two flat glass plates, the bright fringes are 0.6cm apart. 1) How thick is the air wedge 5.0cm from the line of contact of the plates? (the wedge is viewed at normal inc