Current Electricity ധാരാവൈദ്യുതി
The chapter opens at the school science fair (ശാസ്ത്രോത്സവം). An LED glows on a table, joined to a 9 V battery through a switch and two small components. A girl asks: “Why has this component been put in the circuit to make the LED glow?” By the end of the chapter you will answer her. You will learn why electric charges (വൈദ്യുതചാർജ്) flow only when there is a potential difference (പൊട്ടൻഷ്യൽ വ്യത്യാസം), how cells and batteries (സെൽ / ബാറ്ററി) keep that difference going, how to measure current (കറന്റ്) in amperes with an ammeter (അമ്മീറ്റർ), and how resistance (പ്രതിരോധം) controls it through Ohm's law (ഓം നിയമം), V = I R. You will finish with resistors in series (ശ്രേണീരീതി) and parallel (സമാന്തരരീതി) and the wiring of your own house. This interactive self-study guide starts from the basics, explains every idea with Kerala examples, answers every textbook question, and ends with a revision sheet and a model test.
The chapter in one picture
The battery (ബാറ്ററി) is four 1.5 V torch cells in a row, so it gives V = 6 V. The blue dots are free electrons (സ്വതന്ത്ര ഇലക്ട്രോണുകൾ): they leave the battery's − terminal and go round to its + terminal. The conventional current is taken the other way, from + to − in the outer circuit. Slide the sliding contact (സമ്പർക്കകം) of the rheostat (റിയോസ്റ്റാറ്റ്): more coil in the circuit means more resistance R, so less current I, and the bulb glows dimmer. The numbers always obey V = I R (Ohm's law). The bulb is modelled as a fixed 6 Ω resistance. The dots' speed only shows how big the current is: real electrons drift very slowly, but they all start moving the moment the circuit is closed. You will meet every part of this picture on pages 5–10.
How to use this guide
🎬 Watch the animations
Charges drift through wires, cells push, meters read and bulbs brighten, one step at a time. Press Next ▶ or ▶▶ Auto play.
🧪 Do the virtual experiments
Build circuits with the textbook's symbols, join cells in series and in parallel, slide rheostats and plot V–I graphs. Every number is worked out with real physics (V = W/Q, I = Q/t, V = I R). Where the textbook activity has no fixed numbers, the guide uses sample readings – your real readings will differ.
✍️ Try before you see
Every numerical is laid out the exam way: Given → Formula → Substitution → Answer. Use 💡 Show a hint first and work in your notebook. Then open ✅ Show final answer.
📖 Textbook words
Purple മലയാളം words are the exact terms used in your textbook (pages 131–156), so you can match this guide with your book and write answers in either language.
All the experiments in this chapter use torch cells or a 9 V battery. Your textbook says it clearly: do not do these experiments with household electricity. Page 4 explains why, and how to stay safe at home and outdoors in the monsoon.
Learning path
Follow the pages in order. If you are already confident with charges and conductors, “flow needs a difference”, units and graphs, and circuit symbols, you can skim pages 1–4. Still try their quizzes, because the chapter uses these ideas on every page.
Quick glossary (Malayalam ↔ English)
| Textbook term | English | Meaning |
|---|---|---|
| ധാരാവൈദ്യുതി | Current electricity | The chapter title: electricity as a steady flow of charge |
| വൈദ്യുതചാർജ് | Electric charge | Positive or negative; measured in coulombs |
| ഇലക്ട്രോൺ / സ്വതന്ത്ര ഇലക്ട്രോണുകൾ | Electron / free electrons | Tiny negative particles; in a metal some are free to move |
| പോസിറ്റീവ് / നെഗറ്റീവ് | Positive / negative | The two kinds of charge (and the + and − terminals) |
| കൂളോം (C) | Coulomb | The unit of charge |
| കപ്പാസിറ്റർ | Capacitor | Stores electrical energy and gives a current for a short time |
| വൈദ്യുതപ്രവാഹം | Electric current (flow of charge) | Charges flowing through a circuit |
| വൈദ്യുതപ്രവാഹതീവ്രത / കറന്റ് | Intensity of electric current / current | Charge flowing per second: I = Q/t |
| ആമ്പിയർ (A) | Ampere | The unit of current: 1 A = 1 C/s |
| മില്ലി ആമ്പിയർ / മൈക്രോ ആമ്പിയർ | Milliampere / microampere | 1 A = 1000 mA; 1 mA = 1000 µA |
| പൊട്ടൻഷ്യൽ വ്യത്യാസം | Potential difference | Work done to move a unit charge from one point to another: V = W/Q |
| ഇലക്ട്രിക് പൊട്ടൻഷ്യൽ | Electric potential | Potential energy of a unit charge at a point |
| വിദ്യുത്ചാലകബലം (emf) | Electromotive force | Potential difference across a source when no current is drawn – the most it can give |
| വൈദ്യുതസ്രോതസ്സ് | Source of electricity (source of emf) | Keeps a potential difference between two points of a circuit |
| വോൾട്ട് (V) | Volt | The unit of potential difference: 1 V = 1 J/C |
| വോൾട്ട്മീറ്റർ · അമ്മീറ്റർ | Voltmeter · ammeter | Measure potential difference (connected in parallel) · current (connected in series) |
| ക്ലാമ്പ് അമ്മീറ്റർ · മൾട്ടിമീറ്റർ | Clamp ammeter · multimeter | Measures large currents without breaking the circuit · measures V, I and R |
| സെൽ / ബാറ്ററി | Cell / battery | One source / several cells working as one source |
| ഡ്രൈ സെൽ / ബട്ടൺ സെൽ | Dry cell / button cell | Torch cell / small flat cell in watches and calculators |
| പ്രൈമറി സെൽ / സെക്കൻഡറി സെൽ (സംഭരണ സെല്ലുകൾ) | Primary cell / secondary (storage) cells | Cannot be recharged / can be recharged and reused |
| ടെർമിനൽ | Terminal | The + or − end of a cell, or a connecting point of a meter |
| സെല്ലുകളുടെ ക്രമീകരണം | Combination of cells | Joining cells in series or in parallel |
| ശ്രേണീരീതി / സമാന്തരരീതി | Series / parallel connection | One after another in a single path / side by side across the same two points |
| ഷോർട്ട് സെർക്കീട്ട് | Short circuit | The terminals joined by a wire with almost no resistance – dangerous |
| സെർക്കീട്ട് / സെർക്കീട്ട് ഡയഗ്രം | Circuit / circuit diagram | A closed path for current / its drawing with symbols |
| സ്വിച്ച് / കീ | Switch / key | Opens or closes a circuit |
| ചാലകം / ഇൻസുലേറ്റർ | Conductor / insulator | Lets current through easily (many free electrons) / does not (very few) |
| പ്രതിരോധം | Resistance | The property that opposes current: R = V/I |
| പ്രതിരോധകം / റെസിസ്റ്റർ | Resistor | A component that puts a definite resistance into a circuit |
| ഓം (Ω) | Ohm | The unit of resistance: 1 Ω = 1 V/A |
| ഓം നിയമം | Ohm's law | At constant temperature, I is directly proportional to V |
| സഫലപ്രതിരോധം | Effective resistance | The single resistance that has the same effect as a combination |
| ഛേദതല പരപ്പളവ് (വണ്ണം) | Area of cross-section (thickness) | Thicker wire → less resistance |
| നിക്രോം | Nichrome | A high-resistance alloy used in heater coils |
| റിയോസ്റ്റാറ്റ് · സമ്പർക്കകം | Rheostat · sliding contact | A variable resistor · the part you slide to change it |
| അതിചാലകത / അതിചാലകങ്ങൾ | Superconductivity / superconductors | Zero resistance at very low temperatures |
| DC / AC | Direct current / alternating current | One direction only (cells) / changes direction regularly (house supply, 230 V) |
| താപനില · മർദം | Temperature · pressure | Heat flows from higher temperature; air flows from higher pressure (page 2) |
| പ്രവർത്തനം · സയൻസ് ഡയറി | Activity · science diary | Things to do, and the notebook where you write what you observed |
| വിലയിരുത്താം · തുടർപ്രവർത്തനങ്ങൾ | Let us assess · extended activities | The end-of-chapter questions and projects (solved on pages 12–13) |
🌐 Explore online (optional)
Everything in this guide works offline: each page is a single file with no internet needed. Some pages also have blue “🌐 Explore online” boxes. They link to free websites and interactive simulations, including PhET simulations such as the “Circuit Construction Kit”, which your textbook mentions. Those links need internet and open in a new tab. All of them are collected in the resources hub on page 14.
- 📄 Electricity for kids - and everyone else Explain that Stuff
A friendly overview of charge, current, voltage and circuits in one place. - 📄 Electric Eel National Aquarium
A fish that can produce shocks of several hundred volts with living 'cells' stacked like a battery. - 📄 Physics Tutorial - Electric Circuits The Physics Classroom
The full chapter index: charge flow, potential, current, resistance and circuit connections.
Made for self-learning. Works offline – every page is a single file. Study material prepared by Claude for Madhu's family study folder, October 2026.