Understanding Electricity: Static, Current, Circuits, and More
Topic 1: Early Models of Electricity
Two-fluid model (late 1700s) (Dufay)
- Explained two kinds of charges caused by varying amounts of two fluids called vitreous and resinous.
- A neutral object had equal amounts of both fluids.
One-fluid model (1752) (Franklin)
- Explained a charged object as having an excess or deficiency of electrical fluid.
- A neutral object would have the proper amount of fluid.
Topic 2: Atomic Structure and Charge
- Atoms are made of subatomic particles such as protons, which are stationary,
Understanding Electrostatics: History, Matter, and Laws
Electrostatics: An Introduction
Electrostatics: It is the branch of physics that studies the phenomena of electricity produced by static charge distributions, i.e., the electrostatic field of a charged body.
Historical Development
Around 600 BC, the philosopher Thales of Miletus noted the ability of amber, after being rubbed, to exert attraction on small objects. Somewhat later, another Greek, Theophrastus (310 BC), undertook a study of the different materials that were capable of producing electrical
Read MoreUnderstanding Waves: Types, Properties, and Phenomena
Transverse and Longitudinal Waves
Transverse Wave (e.g., Light): Vibrations are perpendicular to the direction of wave motion.
Longitudinal Wave (e.g., Sound): Vibrations are parallel to the direction of wave motion.
Key Wave Properties
- Wavelength: The distance between any two corresponding parts of the wave.
- Amplitude: The maximum distance the wave moves from the equilibrium position.
- Frequency: The number of waves per second.
- Period: The time taken for one complete wave to pass a point.
Wave Phenomena
Diffraction
Diffraction:
Read MoreThermodynamics: Key Concepts and Applications
Fundamental Principles
Under what thermodynamic condition is the change in enthalpy equal to the heat transferred into a system? Constant pressure.
The entropy is associated with what qualitative feature of a system? Disorder.
List two general categories of energy storage at the atomic and molecular level, for subsequent access by cellular biochemistry:
- (1) Chemical reactions [bond formation and breaking]
- (2) Chemical bonding and interactions [molecular recognition]
True or false: Temperature is an extensive
Read MoreUnderstanding Key Physics Principles and Theorems
Steiner’s Theorem
Determining the moment of inertia about an axis of symmetry can be quite complicated by integration. Steiner’s Theorem simplifies this determination. It provides a relationship between the moment of inertia about an axis through a random point of the plane and the moment of inertia about a parallel axis through the center of mass.
Ie = ∫ (x² + y²) dm = ∫ [x² + (d + y)²] dm = ∫ (x² + y²) – 2dy dm + d² ∫ dm = Iz + Md²
Graphical Determination of Instantaneous Center
a)
Read MoreUnderstanding Change of State Graphs: Heating and Cooling
Understanding Change of State Graphs
A change of state graph represents the time and temperature values of a substance as its state changes. Time is the independent variable (x-axis). The x-axis shows time and its units (in parentheses). Temperature is the dependent variable (y-axis). The y-axis shows temperature and its units (in parentheses).
Heating Graphs
In a heating graph (where temperature increases), we can differentiate five sections:
Section 1: Temperature Increase (Solid)
This section is a
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