NCERT Class 8 Science Science: Chapter 11 — Chemical Effects of Electric Current
This chapter, 'Chemical Effects of Electric Current', explores the conductivity of liquids. It begins by reminding students that solids like plastic and wood are poor conductors, while metals are good conductors. The chapter then delves into whether liquids conduct electricity, posing a question about why touching electrical appliances with wet hands is dangerous. It introduces the concept of conductors and poor conductors in the context of liquids. Using a tester, students are guided through activities to determine if liquids like lemon juice or vinegar conduct electricity. The text explains that if a liquid allows current to pass, the tester's bulb glows, indicating a complete circuit. It also addresses situations where the bulb might not glow even with a conducting liquid, suggesting that the current might be too weak to heat the filament sufficiently.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 8 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 11 — Chemical Effects of Electric Current |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 619 |
Learning outcomes
- Understand that some liquids conduct electricity while others do not.
- Identify materials that are good conductors and poor conductors of electricity.
- Explain the working principle of an electric tester.
- Recognize the danger of touching electrical appliances with wet hands.
- Understand why a bulb may not glow even if a liquid is conducting.
Vocabulary
| Word | Meaning |
|---|---|
| Conductor | A material that allows electric current to pass through it. |
| Poor conductor | A material that does not allow electric current to pass through it easily. |
| Electric cell | A device that provides electric current. |
| Tester | A device used to test whether a material conducts electricity. |
| Circuit | A complete path through which electric current can flow. |
| Filament | The thin wire inside a light bulb that glows when heated by electric current. |
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Practice questions
- Name two materials that are good conductors of electricity. Answer: Copper and Aluminium.
- Name two materials that are poor conductors of electricity. Answer: Rubber and Wood.
- Why is it dangerous to touch an electrical appliance with wet hands? Answer: Water is a good conductor of electricity, and wet hands increase the risk of electric shock.
- What is the purpose of a tester? Answer: A tester is used to determine if a material allows electric current to pass through it.
- What happens if the current flowing through a circuit is too weak? Answer: If the current is too weak, the filament of the bulb may not get heated enough to glow.
Frequently asked questions
What are conductors and poor conductors?
Conductors are materials that allow electric current to pass through them easily, like metals. Poor conductors, such as rubber and wood, do not allow current to pass easily.
Can liquids conduct electricity?
Yes, some liquids can conduct electricity, while others are poor conductors. This chapter explores how to test the conductivity of liquids.
Why is it important to use only electric cells for experiments?
It is dangerous to experiment with electricity from the mains or generators. Electric cells are safer for classroom activities.
How does a tester work?
A tester uses a bulb that glows when electric current passes through it, completing a circuit. If the material being tested allows current to flow, the bulb glows.
What might cause a bulb in a tester not to glow?
The bulb might not glow if the connections are loose, the bulb is fused, the cells are used up, or if the liquid being tested is a poor conductor or the current is too weak.
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Topics covered
NCERT Class 8 Science — Science — Chapter 11 — Chemical Effects of Electric Current. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.