Conductor
Comprehensive notes, formulas, and practice questions for Conductor.
Conductor
Conductors & Insulators
What you'll learn
- Conductors allow electric current to pass; insulators do not (under normal conditions).
- Common examples — metals vs plastic, rubber, wood (dry).
- To test materials with a simple tester circuit (cell, bulb, two free wires).
- Safety: insulators protect us from shock; never touch bare mains wires.
Key concepts
Level 1 — Conductors vs insulators
Verbal: In a circuit, current needs a path of conducting material. Insulators block the path.
Visual (tester circuit): Cell → Bulb → Wire → [TEST MATERIAL] → Wire → Cell. Metal key → glows; eraser → no glow.
| Material | Type | Example use |
|---|---|---|
| Copper, iron, aluminium | Conductor | Wires, pins |
| Plastic, rubber, glass (dry) | Insulator | Wire coating, handles |
| Human body (wet skin) | Partial conductor | Danger with mains — never test mains |
Level 2 — Testing, coatings, and safety
Tester: If bulb glows when material connects gap, material is a conductor.
Coated wires: Copper inside (conductor), plastic outside (insulator) — safe to hold.
Liquid conductors (intro): Salt water conducts; pure distilled water poorly — lemon battery extension.
Graphite pencil lead: Conducts — surprising non-metal conductor useful in activities.
Safety rules: Dry hands; low-voltage cells only; insulators on tool handles prevent current reaching you.
Worked example
Test iron nail, plastic scale, and aluminium foil in a bulb tester.
Step 1 — Connect cell-bulb tester with gap between two free wire ends
Step 2 — Touch nail across gap → bulb glows → iron is conductor
Step 3 — Touch plastic scale → no glow → insulator
Step 4 — Touch foil → glows → aluminium is conductor
Step 5 — Record in table: material | bulb glows? | conductor/insulator
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| All non-metals are insulators | Graphite, wet wood conduct | Test before classifying |
| Plastic wire "carries" current | Confusing outer coat with core | Current in metal inside |
| Using mains to test materials | Dangerous lab shortcut | Use 1.5 V / 9 V cell circuits only |
| Bulb doesn't glow → "no electricity" | Open circuit other reason | Check connections; material may still be conductor if path broken elsewhere |
Quick check
- Define conductor and insulator with one example each.
- Why are electric wires covered with plastic?
- Would a copper coin complete a tester circuit? Predict and explain.
- Why should you not touch switches with wet hands?
Open the Practice tab for graded questions on Conductors & Insulators.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
Master this topic with Drishti OS
Get unlimited mock tests, AI-powered mentorship, and complete video courses when you join.
Start Free Practice