Classical Free Electron Theory (Drude Model) and Quantum Comparison
Classical Free Electron Theory and Assumptions
The Classical Free Electron Theory (or Drude-Lorentz model) treats a metal as a container of free electrons (an “electron gas”) moving randomly within a fixed lattice of positive ions. When an external electric field is applied, these electrons experience a force and “drift” in the opposite direction, creating a current.
Assumptions:
Classical Mechanics:
The free electrons are treated as classical particles and obey Maxwell-Boltzmann statistics.
Free Electrons:
Read MoreMagnetic Properties of Materials: Paramagnetism and Ferromagnetism
PARAMAGNETISM
The atoms of paramagnetic substances possess permanent magnetic dipoles.
In the absence of external magnetic field, the atomic dipoles are distributed randomly throughout the paramagnetic material as shown in fig. (5.6a). The external field of individual atoms cancel each other’s effect and hence do not exhibit any magnetic properties in the absence of external magnetic field.
Now, when the substance is subjected to an external field B, each of the atomic dipole experiences a torque.
Read MoreCobalt-60 and Linear Accelerators in Radiation Therapy
Ionizing Radiation Fundamentals
Capable of photons or other particles separating electrons from atoms upon contact. All physical processes involve mass transfer and/or energy processing.
Criteria for Useful Radioactive Sources (Radiophotons)
- Must provide radiation penetrating deep enough to react with the target area.
- Must provide a sufficient amount of energy where the volume is small (If the source has considerable thickness, it absorbs part of the radiation; if it does not, it does not absorb the
Kinematics of Projectiles: Motion, Trajectory, and Formulas
Kinematics of Projectile Motion
Defining Projectiles
- Projectiles are bodies projected into the air that possess both horizontal and vertical components of motion.
- Examples include: shot put, discus, javelin, and the human body during a jump.
- Gravity determines the maximum height achieved by the projectile.
- The horizontal component determines the maximum distance (range) the projectile reaches.
- In real-world scenarios, only air and wind resistance significantly affect the projectile’s motion.
Note on Air
Read MoreEssential Physics Practicals: Methods and Analysis
1. Mass and Weight Relationship Investigation
Step-by-Step Procedure
- Attach the spring balance or Newton meter securely so it hangs vertically.
- Place the first known mass (e.g., 100 g) on the balance hook.
- Wait for the reading to stabilize and record the weight (in Newtons, N).
- Repeat steps 2–3 for several masses (e.g., 200 g, 300 g, 400 g).
- Plot a graph of weight (N) against mass (kg).
Experimental Variables
- Independent: Mass (kg)
- Dependent: Weight (N)
- Control: Location (keep experiment on Earth, constant
Essential Biomechanics Formulas and Human Motion Principles
Core Biomechanics Formulas for Human Motion Analysis
1. Kinematics (Motion Without Forces)
Kinematics describes motion without considering the forces that cause it.
Key Linear Formulas:
- Displacement (Δx):
Δx = x₂ − x₁
Example: If a sprinter moves from 2 m to 8 m → Δx = 6 m
- Velocity (v):
v = Δx / Δt
Example: 6 m in 2 s → v = 6 / 2 = 3 m/s
- Acceleration (a):
a = Δv / Δt
Example: Speed changes from 2 m/s to 6 m/s in 2 s → a = (6−2)/2 = 2 m/s²
Angular Motion Formulas:
- Angular Displacement (θ)