Semiconductor Electronics, P–N Junctions, Atomic Models & AC Physics
Semiconductor Electronics
Semiconductor
Semiconductor — These materials whose electrical conductivity lies between a conductor and an insulator are called semiconductors. At absolute zero they behave as insulators and at room temperature they behave as conductors.
Examples: Ge, Si, GaAs, CdS, CdSe, InP, etc.
Classification by Energy Band Theory
In solids there are three energy bands:
- The lower band is completely filled by electrons and is called the valence band (VB).
- The upper band is called the conduction
Electric Charge, Fields, Potential and Current
Electric Charge and Electric Field
Electric charge — it is a property of a body; charged bodies exhibit attraction and repulsion.
Electric field
Electric field — the sphere around a source charge in which a test charge would experience a force is called the electric field.
Electric field lines
Electric field lines — an electric field is represented by imaginary lines of force which are called electric field lines.
Properties of field lines
- They are imaginary lines of force.
- They are not closed (they
Electric Field, Potential, Capacitance & Current Notes
Chapter 1: Electric Field and Dipole
Electric Field
Electric field: The sphere around a source charge in which a test charge would experience a force is called the electric field.
Electric Field Lines
Electric field lines: An electric field is represented by imaginary lines of force which are called electric field lines.
Properties
- They are imaginary lines of force.
- In the case of a positive source charge they are radially directed outward.
- They are not closed lines.
Mathematical Definition of Electric Field
Mathematically
Read MorePhysics Laboratory Experiments: Ohm’s Law, Diodes, and Magnetism
Experiments in Electricity and Magnetism
Experiment 1: Verifying Ohm’s Law and Determining Resistance
To observe the variation of potential difference (V) across a given resistance with varying current (I), draw the I-V curve, and find the value of the given resistance from the graph.
Apparatus and Materials
- Battery
- Ammeter
- Voltmeter
- Resistance (unknown)
- Rheostat
- Key
- Connecting wires
- Sandpaper
Theory
Ohm’s law states that, provided the temperature remains constant, the current (I) flowing through a conductor
Sports Biomechanics: Levers, Rotation, Newton’s Laws
Third-Class Lever Example: Knee Extension
Q1: An example of a third-class lever is knee extension (like kicking a ball), where the force is between the fulcrum and load. The knee joint is the fulcrum (the pivot point where the lower leg rotates), the quadriceps tendon, inserting on the tibial tuberosity, provides the effort in the middle, and the leg and foot (plus any ball) form the load at the far end.
Landing Technique: Shock Absorption in Gymnastics
Q2: Gymnasts bend their knees and flex their
Read MoreCore Concepts in Radiation Physics, Solar Cells, and Electromagnetism
Radiation Interaction with Matter
1. Alpha (α) Particles
- Heavy, positively charged particles.
- Interact strongly with matter, leading to high ionization.
- Lose energy quickly and stop within a few centimeters of air.
2. Beta (β) Particles
- Fast-moving electrons.
- Moderate interaction, resulting in moderate ionization.
- Can travel a few meters in air.
3. Gamma (γ) Rays
- Electromagnetic waves (no mass, no charge).
- Weak interaction, causing low ionization.
- Travel long distances and penetrate deeply.