Electromagnetic induction
Electromagnetic induction
Top questions
See all →- A conducting rod of length 1 m moves at 5 m/s perpendicular to a uniform magnetic field of 0.4 T on frictionless rails connected through a 4 Ω resistor (other resistances negligible). The external force needed to keep it moving at constant speed is Answer: D. 0.2 N e=Blv=2 V, I=0.5 A, F=BIl=0.4×0.5×1=0.2 N. 1
- When the current in a coil falls uniformly from 2 A to zero in 0.05 s, an emf of 8 V is induced in it. The self-inductance of the coil is Answer: A. 0.2 H L=e/dI/dt=8/2/0.05=0.2 H. 1
- A toroidal ring, having 100 turns per cm of a thin wire is wound on a nonmagnetic metal rod of length 1 m and diameter Data : l = 1 m, d = 1 cm, n = 100 cm⁻¹ = 10⁴ m⁻¹, I = 100 A, µ₀ = 4π × 10⁻⁷ H/m The radius of cross section, r = d/2 = 0.5 cm = 5 × 10⁻³ m (... 2
- The primary and secondary coil of a transformer each have an inductance of 200 × 10-6H. Data: L_P = L_S = 2 × 10⁻⁴ H, M = 4 × 10⁻⁶ H M = K sqrtL_P L_S The coupling coefficient is K = fracMsqrtL_P L_S=frac4 × 10⁻⁶sqrt(2 × 10⁻⁴)²=... 1
- A long solenoid of length l, cross-sectional area A and having N1 turns (primary coil) has a small coil of N2 We assume the solenoid to be ideal and that all the flux from the solenoid passes through the outer coil C. For a steady current Is through... 1
- An emf of 96.0 mV is induced in the windings of a coil when the current in a nearby coil is increasing Data: |e₂| = 9.6 × 10⁻² V, dI₁/dt = 1.2 A/s |e₂| = M fracd I₁d t Mutual inductance, M = frac|e₂|d I₁ / d t=frac9.6 × 10⁻²1.2 = 8 × 10⁻² H =... 1