Curriculum
Physics
Chapter 1 - Electric Current, Ohms Law and Kirchhoffs Laws
0/20
Chapter 2 - Magnetic Effects of Electric Current and Measuring Instruments
0/223.1Use3.2Construction3.3Action3.4Why the parts are used (typical reasons)3.5Sensitivity3.6The ammeter (shunt)3.7The voltmeter (multiplier)3.8Comparison of ammeter and voltmeter3.9The ohmmeter3.10Using the galvanometer to measure current, emf and resistance3.11Analogue and digital instruments3.12Typical "give reasons" for this chapter3.13Summary of formulas
Chapter 3 - Electromagnetic Induction and AC Dynamo and Transformer
0/24Chapter 4 - Alternating Current AC Circuits
0/301.1Alternating current1.2Advantages of AC1.3The hot-wire ammeter1.4Non-inductive ohmic resistor1.5Pure inductor (coil of zero ohmic resistance)1.6Inductive reactance1.7Capacitor and DC1.8Capacitor and AC1.9Capacitive reactance1.10Combinations of capacitors1.11Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula1.12📌 Comprehensive Scientific Terminology Dictionary:1.13🔍 In-Depth Explanations, Deductions & Multi-Book Insights:1.14Lesson summary
2.1Impedance2.2Phase relationships in a series circuit2.3R–L series circuit2.4R–C series circuit2.5R–L–C series circuit2.6Power2.7Variation with frequency2.8Worked examples (new values)2.9The oscillating (LC) circuit2.10Resonance2.11Tuning a radio receiver2.12Summary of formulas2.13Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula2.14📌 Comprehensive Scientific Terminology Dictionary:2.15🔍 In-Depth Explanations, Deductions & Multi-Book Insights:2.16Lesson summary
Chapter 5 - Dual Nature of Wave and Particle
0/331.1Before we start: why "modern" physics?1.2What we already know about light1.3Hot bodies radiate1.4Features of the Planck curve1.5Applications of thermal radiation1.6The black body1.7The failure of classical physics (the "ultraviolet catastrophe")1.8Planck's explanation (1900)1.9Worked examples (Lesson 1)1.10Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula1.11Lesson 1 - Blackbody Radiation, Planck Hypothesis and Photoelectric Effect1.12Lesson summary
2.1Why electrons stay inside a metal2.2Thermionic emission and the cathode-ray tube (CRT)2.3The photoelectric effect2.4Einstein's explanation (1905)2.5Stopping potential and the graphs2.6Using the energy unit eV2.7Worked examples (Lesson 2)2.8The Compton effect2.9Properties of the photon2.10Radiation force (light pressure)2.11Macroscopic and microscopic models of light2.12Reflection or transmission of photons2.13Worked examples (Lesson 3)2.14De Broglie's idea (1923)2.15Why do we not notice the wave nature of a ball?2.16Wavelength of an accelerated electron2.17The electron microscope2.18Comparison: optical and electron microscope2.19Worked examples (Lesson 4)2.20Chapter summary (key points)2.21Common mistakes to avoid
Chapter 6 - Atomic Spectra and X-Rays
0/281.1Why a new model was needed1.2Bohr's postulates (hydrogen atom)1.3Radii and energies of the hydrogen atom1.4Excitation and emission in hydrogen1.5The series of the hydrogen spectrum1.6Limitations1.7Worked examples (Lesson 1)1.8The spectrometer1.9Types of spectra1.10Worked examples (Lesson 2)1.11What are X-rays?1.12Properties of X-rays1.13Production: the Coolidge tube1.14The X-ray spectrum1.15Origin of the characteristic radiation1.16Origin of the continuous radiation (bremsstrahlung)1.17Comparison of characteristic and continuous X-rays1.18Applications of X-rays1.19Worked examples (Lesson 3)1.20Going deeper — how Bohr's numbers are obtained, and a problem-solving workshop1.21Derivation of the radius and energy (hydrogen)1.22Understanding the energy-level diagram1.23Ionisation, excitation and de-excitation1.24More worked examples1.25X-ray quantities for practice1.26Exam-style reasoning guide1.27Chapter summary1.28Common mistakes
Chapter 7 - Lasers and Principles
0/311.1Energy levels and transitions1.2Comparison between spontaneous and stimulated emission1.3Worked examples (Lesson 1)1.4Properties of the laser beam1.5Monochromaticity (spectral purity)1.6Collimation (a parallel narrow beam)1.7Coherence1.8Intensity (concentration)1.9Worked examples (Lesson 2)1.10Population inversion1.11The three essential elements of any laser1.12Laser action step by step1.13Worked examples (Lesson 3)1.14Construction1.15Operation1.16Applications of lasers1.17Holography (3-D photography)1.18Medicine1.19Other applications1.20Why a threshold? (gain versus loss)1.21Continuous and pulsed operation1.22A guide to common lasers1.23Eye safety and classes1.24Photon arithmetic for laser problems1.25Typical exam questions and model answers (outline)1.26Chapter summary1.27Common mistakes1.28Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula1.29📌 Comprehensive Scientific Terminology Dictionary:1.30🔍 In-Depth Explanations, Deductions & Multi-Book Insights:1.31Lesson summary
Chapter 8 - Modern Electronics and Semiconductors
0/311.1Conductors, insulators and semiconductors1.2The silicon crystal1.3Free electrons and holes1.4Motion of holes1.5Conduction in a semiconductor compared with a metal1.6Sensitivity of semiconductors1.7Worked examples (Lesson 1)1.8Why dope?1.9n-type semiconductor (donor impurities)1.10p-type semiconductor (acceptor impurities)1.11The law of mass action1.12Summary comparison1.13Worked examples (Lesson 2)1.14Formation of the junction1.15Biasing the junction1.16The diode as a switch and as a rectifier1.17Electronic tuning (the varactor)1.18Worked examples (Lesson 3)1.19Structure1.20Operation (n-p-n, common base)1.21Current ratios1.22The transistor as an amplifier1.23The transistor as a switch (and inverter)1.24Worked examples (Lesson 4)
More lessons
0/831.1Key terms1.2Laws and key relationships1.3Boyle's Law and Isothermal Compression Mechanics1.4Charles's Law, Absolute Zero, and the Kelvin Temperature Scale1.5The General Gas Law and Ideal Gas Mixtures1.6Comparison1.7Worked examples1.8Exam tips1.9Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula1.10🔍 In-Depth Explanations, Deductions & Multi-Book Insights:
2.1Key terms2.2Laws and key relationships2.3Intensive Physics of Density and Non-Contracting Fluid Mixtures2.4Liquid Pressure at Depth and Manometric Measuring Instruments2.5Pascal's Principle and Hydraulic Systems2.6Worked examples2.7Exam tips2.8Real-world applications2.9Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula2.10📌 Comprehensive Scientific Terminology Dictionary:2.11🔍 In-Depth Explanations, Deductions & Multi-Book Insights:
4.1Key terms4.2Laws and key relationships4.3Torricellian Barometer and Standard Atmospheric Pressure4.4The U-Tube Manometer and Immiscible Fluids Hydrostatic Equilibrium4.5Pascal's Principle and Hydraulic Engineering Systems4.6Comparison4.7Worked examples4.8Exam tips4.9Key Scientific Tables & Anatomical Diagrams Extracted from Official Curricula4.10🔍 In-Depth Explanations, Deductions & Multi-Book Insights:4.11Lesson summary
Text lesson
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR)
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR)
Overview
Overview
🌳 Concept tree
Lesson 2→Digital Electronics and Logic Gates (NOT, AND, OR)
├── Analog and digital signals
├── The binary number system
├── The advantage of digital systems→immunity to noise
├── Logic gates
├── Worked examples (Lesson 5)
├── Chapter summary
└── Common mistakes
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 1 / 9
Analog and digital signals
Analog and digital signals
- All electronic systems deal with natural quantities (sound, light, temperature) by converting them to electrical signals; for example, the microphone converts sound to a voltage, the video camera converts an image to electric signals.
- In TV, picture and sound are converted to electrical signals, then to electromagnetic waves at the transmitter, and back to electrical signals at the receiver.
- Electronics in which the signal can take any value in a continuous range, imitating the natural quantity, is called analog electronics.
- In digital electronics the signal has only two possible values representing two states, 0 and 1 (low and high voltage).
- Any number, letter or symbol is encoded as a string of 0’s and 1’s (the binary system).
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 2 / 9
The binary number system
The binary number system
- The decimal system uses ten digits and weights 100, 101, 102, … For example 17 = 1 × 101 + 7 × 100.
- The binary system has two digits (0 and 1) and weights 20, 21, 22, 23 … For example:
3 = 1 × 21 + 1 × 20 = 11₂
5 = 1 × 22 + 0 × 21 + 1 × 20 = 101₂
13 = 8 + 4 + 0 + 1 = 1101₂
- 10110₂ = 16 + 0 + 4 + 2 + 0 = 22.
- With n binary digits (bits) we can represent 2n different values: 8 bits give 256 values.
- An analog-to-digital converter (ADC) encodes the natural signal into binary code; at the receiver a digital-to-analog converter (DAC) decodes it back.
- Pictures are divided into tiny elements called pixels and each is coded.
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 3 / 9
The advantage of digital systems: immunity to noise
The advantage of digital systems: immunity to noise
- In nature there are unwanted, random signals called electrical noise, caused by the random motion of electrons (charged particles whose random motion causes minute fluctuating currents).
- Noise disturbs the information carried by an analog signal, and cannot easily be removed: in a weak radio station it is heard as a hiss, in a weak TV station (or with a poor antenna) it appears as "salt and pepper" spots.
- In a digital system the information is not in the exact voltage but in whether the signal is the 0 state or the 1 state; a small noise added to either value does not change its state, so the information is recovered exactly.
- This is the main advantage of digital electronics, and it is why mobile telephony, digital satellite TV, CDs and computers are digital.
- The computer must convert everything (numbers, letters, images) to binary code.
- It performs all calculations using Boolean (binary) algebra.
- It stores information temporarily in RAM (random access memory) and permanently on the hard disk, in which small regions are magnetised in one direction for 0 and the opposite direction for 1.
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 4 / 9
Logic gates
Logic gates
- The circuits that perform logic operations on binary signals are called logic gates.
- They are the building blocks of computers and communication systems and are made from transistors (as switches).
- The basic gates are:
- 1) NOT gate (inverter) one input, one output; the output is the opposite of the input.
| A | Y = NOT A |
|---|---|
| 0 | 1 |
| 1 | 0 |
Switch analogya switch in parallel with the lamp: when the switch is closed (on) the lamp is off, and vice versa.
2) AND gatetwo or more inputs and one output; the output is 1 only if all inputs are 1 (the "coincidence" gate).
| A | B | Y = A AND B |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
Switch analogytwo switches in series with a lamp: both must be closed for the lamp to light.
3) OR gatetwo or more inputs and one output; the output is 1 if at least one input is 1 (the "optionality" gate).
| A | B | Y = A OR B |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
Switch analogytwo switches in parallel with a lamp: closing either one lights the lamp.
Combined gates.Placing a NOT gate after an AND gate gives NAND; after an OR gate it gives NOR:
| A | B | AND | NAND (= NOT AND) | OR | NOR (= NOT OR) |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 1 | 0 | 1 |
| 0 | 1 | 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 1 | 1 | 0 |
| 1 | 1 | 1 | 0 | 1 | 0 |
- All the operations of a computer are built from such gates.
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 5 / 9
Worked examples (Lesson 5)
Worked examples (Lesson 5)
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Example 5.1 — binary conversion. | Convert 45 to binary: 45 = 32 + 8 + 4 + 1 = 101101₂. Convert 1001₂ to decimal: 8 + 0 + 0 + 1 = 9 | Convert101101₂1001₂decimal |
| Example 5.2 — a compound circuit. |
| outputgateinputsfeeds |
| Example 5.3 — truth table of "AND followed by NOT". |
| Rows |
| Example 5.4 — number of bits. | To store 1000 different values you need 10 bits (210 = 1024) | store1000differentvalues |
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 6 / 9
Chapter summary
Chapter summary
| Comparison aspect | Main idea | Keywords |
|---|---|---|
| Metal |
| positiveionscloudfree |
| • |
| Conductivitysemiconductordependscarriers |
| Doping |
| pentavalentdonorsgivetype |
| p-n junction (diode) |
| depletionregioninternalfield |
| Transistor (n-p-n or p-n-p) |
| Usedamplifierswitchinverter |
| • |
| Digitalelectronicsencodesinformation |
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 7 / 9
Common mistakes
Common mistakes
- A donor atom becomes a positive ion in n-type material; an acceptor becomes a negative ion in p-type material. The crystal as a whole is neutral.
- The "n" and "p" in the junction refer to carriers’ sign in the regions, not to the charge of the whole region.
- Forward bias = p to positive terminal.
- α is slightly less than 1, β is large; never swap them.
- In digital circuits, a high input to the transistor switch gives a low output.
- .egp-ex{margin:18px 0;border:1px solid rgba(79,63,224,.2);border-radius:16px;overflow:hidden;background:#fff}.egp-ex-h{padding:10px 16px;font-weight:800;background:linear-gradient(90deg,#4f3fe0,#22c1c3);color:#fff}.egp-ex-tabs{display:flex;flex-wrap:wrap;gap:6px;padding:10px 12px;background:#f7f6ff}.egp-ex-b{border:1px solid rgba(79,63,224,.3);background:#fff;border-radius:20px;padding:5px 14px;font-weight:700;cursor:pointer}.egp-ex-b.on{background:#4f3fe0;color:#fff}.egp-ex-p{padding:12px 16px}
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 8 / 9
Part 9
Part 9
- 📖
🔍 In-Depth Explanations, Deductions & Multi-Book Insights:
Physics (Thanaweya Amma 2026/2027)
- Lesson 2 – Digital Electronics and Logic Gates (NOT, AND, OR)
- Analog electronics processes continuous voltage variations vulnerable to noise.
- Digital electronics processes discrete binary logic (0 and 1) offering superior noise immunity.
- Logic gates (NOT, AND, OR) form the computational building blocks of microprocessors.
🌳 Conceptual Hierarchy Tree
Digital Systems and Logic Gates
├── 1. Analog vs. Digital Signals
│ ├── AnalogContinuous waveform susceptible to atmospheric noise distortion
│ └── DigitalBinary pulses (High 1 / Low 0) easily cleaned by filtering noise
└── 2. Fundamental Logic Gates
├── NOT Gate (Inverter1 input, 1 output): Output = A̅ (Flips 0 to 1, and 1 to 0)
├── AND Gate (Conjunction2+ inputs, 1 output): Output = A · B (1 only if ALL inputs are 1)
└── OR Gate (Disjunction2+ inputs, 1 output): Output = A + B (1 if ANY input is 1)
📋 Master Teacher's Blackboard Secrets
RULE 1NOT Gate has only ONE input and ONE output: Output is always the inverse of input.
RULE 2AND Gate output is 1 ONLY when ALL inputs are 1 (equivalent to series switches).
RULE 3OR Gate output is 0 ONLY when ALL inputs are 0 (equivalent to parallel switches).
📊 MatrixLogic Gates Truth Tables Combined Matrix
| Input A | Input B | NOT Gate (A̅) | AND Gate (A · B) | OR Gate (A + B) |
|---|---|---|---|---|
| 0 | 0 | 1 | 0 | 0 |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 0 | 1 |
| 1 | 1 | 0 | 1 | 1 |
Lesson 2: Digital Electronics and Logic Gates (NOT, AND, OR) · 9 / 9
Well done! You finished this lesson
What would you like to do next?