Physics — Classical Mechanics — Kinematics and Dynamics + 5 more topics

When we talk about optics, we're essentially discussing how light interacts with matter and what happens as it travels. The field is broadly split into two distinct, yet complementary, approaches: geometric optics and physical optics. Each is a model, or a way of thinking about light, that's useful in different situations.

This is the simpler model and it's super useful for understanding things like cameras, telescopes, and eyeglasses. Geometric optics assumes light travels in straight lines called rays. When these rays hit a surface, they either bounce off (reflection) or pass through and bend (refraction).

Classical mechanics, specifically kinematics and dynamics, is about understanding motion without getting into quantum weirdness or speeds near light. It's the physics of everyday objects.

Kinematics focuses on describing an object's motion using these key quantities:

An oscillation is just a fancy word for something moving back and forth around a central point, like a spring bouncing or a child on a swing. The key properties are:

• Period (T): How long it takes for one full back-and-forth cycle. Measured in seconds.
• Frequency (f): How many cycles happen per second. Measured in Hertz (Hz), where f = 1/T.
• Amplitude: The maximum distance the object moves from its central, equilibrium position.

These are related by Ohm's Law: $V = I \times R$.

Here's a basic flow for how a circuit operates:

Since they're in series, the total resistance is the sum of all resistances:
$R_{total} = R_{LED1} + R_{LED2} + R_{resistor}$
$R_{total} = 330 \Omega + 330 \Omega + 100 \Omega = 760 \Omega$

Now, using Ohm's Law to find the total current flowing through the circuit:
$I = V / R_{total}$
$I = 9V / 760 \Omega \approx 0.0118 A$ or $11.8 mA$

Modern physics branches into two main areas, tackling the limits of classical physics: Relativity (dealing with the very fast and very massive) and Quantum Mechanics (dealing with the very small).

Special Relativity, developed by Albert Einstein, focuses on how motion affects measurements when objects move at speeds approaching the speed of light. It's built on two core postulates: