Magnetic Effects of Electric Current — Karnataka (SSLC) Class 10 Science Solutions (Free)

A magnetic field is the region of space around a magnet or current-carrying conductor where magnetic force is experienced. For a straight wire carrying current I, magnetic field strength B = μ₀I/(2πr), where r is perpendicular distance. Direction given by right-hand rule: thumb along current, fingers curl around wire showing field direction.

Fleming's left-hand rule: Thumb (motion), First finger (field), seCond finger (current). Force on conductor: F = BIL sinθ, where B = magnetic field, I = current, L = length of conductor, θ = angle between B and I. When perpendicular (θ = 90°), F is maximum.

Motor: rectangular coil in magnetic field rotates when current flows. Lorentz force on coil sides is perpendicular, creating torque. Commutator (split ring) reverses current direction every half rotation, keeping torque always in same direction. This continuous rotation converts electrical energy to mechanical motion.

Electromagnetic induction is the production of induced EMF in a conductor due to changing magnetic flux. Faraday's law: induced EMF = -dΦ/dt, where Φ is magnetic flux (B⋅A). Negative sign (Lenz's law) indicates induced current opposes the change causing it. Used in generators and transformers.

Galvanometer: sensitive device detecting small currents. Ammeter: measures large currents, low resistance (≈0), connected in series. Voltmeter: measures potential difference, high resistance (≈∞), connected in parallel. Ammeter from galvanometer: add shunt (low R). Voltmeter from galvanometer: add multiplier (high R).