Govt. Exams
Bismuth is a diamagnetic material that gets repelled by magnetic fields. Iron, cobalt, and nickel are ferromagnetic materials.
Using Faraday's law: EMF = ΔΦ/Δt = BA/Δt = 2 × (0.05 × 0.1)/0.1 = 1 V
Transformer equation: V₂/V₁ = N₂/N₁ (ideal transformer with no losses)
Magnetic moment of a current loop: μ = IA, where I is current and A is area of the loop
Cyclotron frequency: f = qB/(2πm) = ω/(2π), where ω = qB/m is the angular frequency
Magnetic force per unit length between parallel wires: F/L = μ₀I₁I₂/(2πd), attractive for same direction currents
For circular motion in magnetic field: qvB = mv²/r, therefore r = mv/(qB)
Using Ampere's circuital law for an infinite straight wire: B = μ₀I/(2πr), where μ₀ = 4π × 10⁻⁷ T·m/A
Torque on a magnetic dipole: τ = M × B = MB sin θ, where θ is the angle between M and B.
An ideal solenoid produces a uniform, strong magnetic field inside (B = μ₀nI) and negligible field outside. This is due to cancellation of fields from adjacent turns outside.
