12
CBSE Marks
★★★★★
Difficulty
12
Topics
Very High
Board Weight
Topics Covered
12 key topics in this chapter
Magnetic Field & Field Lines
Field due to Current-Carrying Conductor
Right-Hand Thumb Rule
Solenoid & Magnetic Field
Force on a Current in Magnetic Field
Fleming's Left-Hand Rule
Electric Motor
Electromagnetic Induction
Faraday's Law (qualitative)
Fleming's Right-Hand Rule
Electric Generator
Domestic Circuits: AC vs DC
Study Resources
Key Formulas & Reactions
| Formula / Reaction / Rule | Expression |
|---|---|
| Force on Conductor | \(F = BIL sinθ\) |
| Magnetic Field (wire) | \(B ∝ I/r (around straight wire)\) |
| Solenoid | \(Field inside ≈ uniform; outside ≈ bar magnet\) |
| Faraday's Law | \(EMF induced = rate of change of magnetic flux\) |
| Fleming LHR | \(Field (fore) + Current (mid) → Force (thumb)\) |
| Fleming RHR | \(Field (fore) + Motion (thumb) → Current (mid)\) |
| AC Frequency (India) | \(50 Hz | Household voltage: 220 V\) |
Important Points to Remember
Right-hand thumb rule: point thumb in direction of current, fingers curl in direction of magnetic field lines around a conductor.
Fleming's Left-Hand Rule (motor effect): forefinger = field (B), middle finger = current (I), thumb = force (F/motion).
Fleming's Right-Hand Rule (generator effect): forefinger = field, thumb = motion, middle finger = induced current.
AC is generated in power plants and preferred for long-distance transmission (step-up/down transformers). DC is used in batteries.