Induction, Generator and Domestic Circuits
NCERT Class 10 • Science • Chapter "Magnetic Effects of Electric Current"
Induction, Generator and Domestic Circuits
If a current produces a magnetic field, the reverse also happens: a changing magnetic field produces a current. This is electromagnetic induction, discovered by Faraday, and the whole of modern power generation rests on it.
Induction and the Generator
- When a conductor is moved in a magnetic field, or the field around it changes, a current is induced in the conductor.
- The direction of the induced current is given by Fleming's right hand rule.
- An electric generator converts mechanical energy into electrical energy using this principle.
- It has a coil rotating in a magnetic field; the rotation changes the field through the coil and induces a current.
- Alternating current reverses its direction periodically, while direct current flows in one direction only.
- The supply in Indian homes is alternating current at 50 hertz, which means the direction reverses fifty times each second.
- Alternating current is used for supply because it can be transmitted over long distances with less loss and its voltage can be changed easily.
Domestic Wiring and Safety
- Domestic supply reaches a house through three wires: live, neutral and earth.
- The live wire carries the supply voltage, the neutral completes the circuit, and the earth wire is a safety connection to the ground.
- A switch and fuse are always placed in the live wire, so that turning the switch off truly cuts the supply.
- Appliances are connected in parallel so that each gets the full voltage and works independently.
- Overloading happens when too many appliances draw current together, and a short circuit when live and neutral touch.
- The earth wire carries any leaked current safely into the ground and prevents a severe shock from a metal body.
- Miniature circuit breakers are now used in place of fuses because they can be reset instead of replaced.
| Wire | Function | Usual Colour Convention |
|---|---|---|
| Live | Carries the supply voltage | Red or brown |
| Neutral | Completes the circuit | Black or blue |
| Earth | Safety connection to the ground | Green |
Electromagnetic induction — the production of a current in a conductor by a changing magnetic field around it.
Exam me kaise aata hai
- Who discovered electromagnetic induction — Faraday
- Direction of induced current is given by — Fleming's right hand rule
- The frequency of supply in Indian homes is — 50 hertz
- A fuse and switch are placed in which wire — the live wire
UPSC/State PSC ke liye
- Alternating current is preferred for transmission because transformers can raise its voltage for long distance travel and lower it again for use, which is not possible with direct current in the same simple way.
- The switch must be in the live wire, because if it were in the neutral the appliance would remain at supply potential even when switched off.
Yahan confuse hote hain
✗ A generator converts electrical energy into mechanical energy | That is a motor; a generator does the reverse | ✓
✗ The switch may be placed in the neutral wire | It must be in the live wire for safety | ✓
✗ Direct current is used for household supply in India | Household supply is alternating current at 50 hertz | ✓
Ek nazar me
- A changing magnetic field induces a current, which is electromagnetic induction.
- A generator turns mechanical energy into electrical energy.
- Indian domestic supply is alternating current at 50 hertz.
- Live, neutral and earth wires; switch and fuse always in the live wire.
Ab practice karein
Electricity aur magnetism se har exam me formula aur concept dono aate hain. ExamAtlas ke mock test se abhi jaanchein.