Heat and Thermodynamics Chapter 11

Study Notes

Heat is considered as weightless fluid (caloric theory) but this theory is flawed
Heat is a form of energy that flows from a hot body to a cold body due to temperature difference
Heat's unit is Joule (1 calorie = 4.18 J)
Heat is the total kinetic energy of molecules
Heat transfer occurs through three methods:
Conduction (atoms to atoms) - slowest
Convection (molecule movement) - in liquids
Radiation (electromagnetic waves) - fastest
Heat is the change in energy through random motion, less efficient ; Work is through ordered motion, more efficient
Internal energy is a state function, sum of KE and PE of molecules
Temperature is the measure of the intensity of heat
Scales of temperature: Celsius (0°C = ice point, 100°C = steam point), Fahrenheit (32°F = ice point, 212°F = steam point), Kelvin (0K = absolute zero)

Charge is a property of a substance obtained by adding or removing electrons
There are two types of charge: positive (deficiency of electrons) and negative (excess of electrons)
Charge is conserved and quantized; electrons are the smallest units of charge
Electrification occurs through three methods: friction, conduction, and induction
Coulomb's Law: the force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them.
Coulomb's constant (k) is a constant for a given medium

Conductors have free electrons, insulators don't
Drift velocity is the average velocity of electrons due to an electric field
Electric current is the rate of flow of charge
Ohm's Law: current is directly proportional to voltage and inversely proportional to resistance
Resistance depends on length, cross-sectional area, material, and temperature
Resistors can be connected in series or parallel to change the overall resistance of the circuit
Emf is the work done per unit charge by a source of energy.

Electromagnetism deals with the magnetic effects of electric currents
Magnetic field is the region surrounding a magnet, or a current-carrying conductor
Magnetic field intensity depends on current strength, distance, and presence of magnetic material

Galvanometers: measure small currents. They can be modified to measure voltage or resistance
Ammeters: measure current; connected in series in the circuit
Voltmeters: measure voltage; connected in parallel across the circuit
Wheatstone bridge: a circuit that can be used to measure unknown resistance

Electromagnetic waves don't require a medium and are composed of oscillating electric and magnetic fields
Modulation is the process of varying the characteristics of a high-frequency carrier wave according to the instructions of a low-frequency signal
Types of modulation include amplitude modulation (AM) and frequency modulation (FM)

Frames of reference: a set of coordinates used for describing the position and motion of an object, either inertial or non-inertial
Special Theory of Relativity: deals with the relationships in the presence of constant velocity
Length contraction: Length of an object changes in the direction of motion compared to the observer's frame
Time dilation: Time slows down for objects in motion compared to a stationary observer
Mass-energy relationship: mass and energy are interchangeable (E=mc²)

Bohr's atomic model provided a model for the structure of the atom, explaining spectral lines and electron orbit radii and energy levels. Bohr model of atom
X-rays and gamma rays are shorter wavelengths emitted by certain atomic transitions

The nucleus is the dense, positively charged central region of an atom containing protons and neutrons
Isotopes of an element: atoms of the same element with the same atomic number but different mass numbers
Radioactivity is the spontaneous disintegration of unstable atomic nuclei accompanied by the emission of radiation

Alpha particles (helium nuclei): low penetrating power, positive charge
Beta particles (high-speed electrons): moderate penetrating power, negative charge
Gamma rays (high-frequency electromagnetic radiation): high penetrating power, no charge
Geiger counter: A device for detecting the presence of ionizing radiation