Lab 6: Geometrical Optics, Telescope
Telescopes are used to view objects at long distances away, where the lenses in the
telescope magnify the actual size of the image to a larger, clearer perceived image. For a simple
telescope, two components a
Photon energy and momentum relations
In 1905, in order to the explain the photoelectric effect, Albert Einstein postulated
that light was made up of particles, which we now call photons.
The energy of a single photon is r
Diffraction gratings, x-ray
So far we have considered two infinitely-narrow slits (Youngs interference) and a
single slit of finite width.
Here we shall consider the diffraction grating, which we can think
Thin-film interference, Diffraction
Hard and soft reflections
When light propagates from one material to another, the reflected wave can undergo a phase change, depending wether the refractive index increases or decreases.
When na > nb (so
Molecular speeds, first law, work,
paths, internal energy
Maxwell-Boltzmann speed distribution
Statistical physics says that, at a temperature T , the probability of a system being
in a state with energy E is
P (E) =
1 E/kB T
van der Waals, heat capacities
van der Waals equation
The ideal gas law works well at low densities or high temperatures, where the
interaction between molecules can be neglected.
For more difficult conditions, empirical corrections can be m
Light propagation, Huygens
Wavefronts and rays
Let us develop the wave-like propagation of light further.
Recall that a wavefront is the collection of all points that have the same phase.
Wavefront, phase = constant
Heat capacity, phase changes
If we heat a rod that is not allowed to expand, stress is generated.
Picture this as follows: First heat the rod and allow it to expand. Then compress
it back to its original length.
Reversibility, heat engines
Thermodynamic processes have a direction associated with them, e.g. heat flows
from hot cold.
Note: cold hot would not violate 1st law, but it never occurs. Natural processes
Microscopic view of entropy
Boltzmann proposed that the entropy of a macroscopic state is
S = kB ln W
Ludwig Boltzmanns epitaph
where W is the number of microstates corresponding to the given macroscopic
Internal energy, ideal gas,
Phase change at constant T and P
1 cm3 of water (1 g) at T = 100 C becomes 1671 cm3 steam when boiled at
constant P = 1 atm. The heat of vapourization is LV = 2.256 106 J/kg.
What is the change
Entropy statement of the second law
If we account for entropy changes in both the system and the surroundings, then:
1. For an irreversible process, the increases in entropy outweigh any decreases in
2. For a re
Refraction at spherical surfaces
This is the study of image formation using lenses.
In fact, an ideal lens has parabolic surfaces, not spherical surfaces. But the difference shows up only when one goes beyond the paraxial approximat
Molecular view of matter, kinetics
Equations of state
The variables needed to specify the state of a system are the mechanical variables
and the temperature T . For a pure gas or liquid we need P, V, T, n. For a mixture
of gases, we also nee
Lab 5: The Statistical View of Entropy
The group are taught that entropy of a system increases as a system tends towards
equilibrium, and it doesnt seem reasonable for a system to become less chaotic over time, but
is it possible for a system to
Lab 3: Mechanical Equivalent of Heat
Abstract - 10%
Students will learn about The First Law of Thermodynamics as Applied to a Mechanical
System. In the past it was believed that thermal energy was like a physical liquid flowing from
one object to another.
Lab 2: Gas Thermometer
Scientists have known about absolute zero for a long time now, but how? -273.15 (or
0K) is such a difficult temperature to physically reach. It turns out that theyve done this in the
past by measuring pressure and volume wi
Lab 7: Microwaves
In Part 1 of the this lab, the group found the most current to be at 0, or when the
transmitter and receiver are level with each other, at 12 mA, while the predicted lowest current
would occur when the transmitter is at 90 to th
Lab 4: Gas Compression and Expansion
The lab consisted of testing adiabatic, no heat exchange, and isothermal, no change in
temperature, processes by compressing and expanding gases using a syringe. Volumes were
measured using the units marked on
Lab 8: Interference
In this laboratory experiment, students studied the behaviors of interference and
diffraction and used these concepts to measure and calculate values including wavelength,
aperture diameter, and slit separation. In part 1, the
To understand images and image formation, all we need is
Ray model of light
Laws of refraction and reflection
Geometry and trigonometry
The key role played by geometry is the reason for the name geometric
Maxwell gives light
Light is mysterious. Newton thought that light was made up of particles the
corpuscular nature of light. However, for a long time that point of view was abandoned by many, notably Huygens, Euler, Fresnel, and oth
Thermodynamics, Optics, and Modern Physics
Prof. Christian Dwyer
Physical Sciences F-wing, room PSF 336
Instructor: Associate Professor Christian Dwyer
Lecture schedule: Mondays and
Internal reflection, polarization
Total internal reflection
Total internal reflection occurs when one of the s in Snells law is greater than
or equal to 90 .
Consider rays travelling from medium 1 to medium 2 with n1 > n2 (e.g., water
Interference of light
Coherence and interference
When examining interference phenomena we must use the wave description of light
(unlike geometric optics, where only the ray part of the description was needed).
Suppose we have a small poin
Second law, refrigerators, entropy
A refrigerator is essentially a heat engine operating in reverse. Hence we just
reverse the flows of heat and work.
Recall, a heat engine absorbs heat energy |QH | from a heat bath and release