When variable loss becomes equal to the constant loss, efficiency is maximum. Losses = Pi + Pc Since copper loss is a variable loss therefore Losses = Pi + Pi = 2pi Thus at a maximum efficiency of this transformer total loss = 150 x 2 = 300 W
The inductance of the coil is given by the relation L = Nφ/I Where N = number of turns = 50 φ = flux = 200μWb I = current = 8 A L = 50 × 200 × 10−6 ⁄ 8 L = 1.25 mH
Given Inductance L = 2 H Rate of change of current di/dt = 5 A/sec Self induced EMF = − (Rate of change of current × Inductance) = −L(di/dt) = −(5 × 2) = −10V
Magnetic Field Strength (H) gives the quantitative measure of strongness or weakness of the magnetic field.
H = B/μo
Where
B = Magnetic Flux Density
μo = Vacuum Permeability
Magnetic Field strength at the center of circular loop carrying current I is given by
B = μoI/2r
B/μo = I/2r
H = I/2r
Where r = Radius
Now Given Parameters
Diameter = 1m
Current = 2A
∴ Magnetic field Intensity H = (2 / 2 × 1/2) = 2 A/m
EXAMIANS