Galvanized steel conductors do not corrode, and possess high resistance. Hence such Wires are used in telecommunications circuits, earth wires, guard wire, stray wire, etc.
The luminous efficiency of an electric lamp is the ratio of the luminous flux (in lumen) emitted by the lamp to the electric power (watt) given to it i.e.
Luminous efficiency η = Luminous flux/Watt
Note:- Lumens is the unit of measurement for luminous flux, which is the total amount of visible light emitted by a source.
L0ad impedance Z = R + jX
z = 10 + 10j
Phase angle θ= tan−1(IL/IR)
tanθ = 1
Mutual inductance between two coupled coils is given by the relation
M = K√L1L2
L1L2 = Inductance of the coil
K = Coefficient of coupling
When K = 1 coils are said to be tightly coupled and if K is a fraction the coils are said to be loosely coupled.
∴ m ≤ (L1 L2 )0.5