Electromagnetism — Telangana (SSC) Class 10 Science Solutions (Free)

An electromagnet is a magnet created by passing electric current through a coil of insulated wire wound around an iron core. Construction: Insulated copper wire coiled around soft iron core + power source Differences from permanent magnet: 1. Electromagnet requires electric current to be magnetic; permanent magnet has permanent magnetism 2. Strength of electromagnet can be controlled; permanent magnet has fixed strength 3. Electromagnet can be switched on/off; permanent magnet cannot 4. Electr…

Faraday's Law: The induced EMF in a coil is directly proportional to the rate of change of magnetic flux through it. Mathematically: e = -N(dΦ/dt) where e = induced EMF, N = number of turns, dΦ/dt = rate of change of magnetic flux Explanation: When magnetic field through a coil changes, an EMF (voltage) is induced. The negative sign indicates direction (Lenz's Law). Practical example: Moving magnet near coil → magnetic field changes → EMF induced → current flows if circuit is closed

Fleming's Left Hand Rule (Force on current-carrying wire in magnetic field): Thumb = direction of force, Index finger = direction of magnetic field, Middle finger = direction of current Application: Determines force direction in electric motors Fleming's Right Hand Rule (Induced EMF/current in moving conductor): Thumb = direction of motion, Index finger = direction of magnetic field, Middle finger = direction of induced current Application: Determines induced current direction in generators

Construction: • Rectangular coil of insulated copper wire • Placed between two poles of a permanent magnet (N and S) • Connected to a split-ring commutator • Commutator rotates with coil, maintaining circuit contact via brushes Working: Step 1: Current enters coil via commutator Step 2: Magnetic force acts on current-carrying coil (Fleming's Left Hand Rule) Step 3: Coil rotates; commutator switches current direction at each half rotation Step 4: Force always acts in same rotational direction → …

Construction: • Rectangular coil rotating between magnetic poles (N-S) • Slip rings attached to coil ends • Brushes maintain circuit contact with slip rings • External circuit/load connected via brushes Working: Step 1: Coil rotates in magnetic field (mechanical energy input) Step 2: Magnetic flux through coil changes continuously Step 3: Rate of flux change induces EMF (Faraday's Law) Step 4: Induced EMF is sinusoidal: e = e₀sin(ωt) Step 5: Current flows in external circuit Principle: Convert…