In an AC generator when the plane of the armature is perpendicular to the magnetic field, what will the magnitude of the magnetic flux passing through the coil and the emf induced in the coil be?
The magnetic flux is maximum and the induced emf is zero
In an AC generator, the magnetic flux through the coil is given by Φ = B A cosθ, where θ is the angle between the plane of the coil and the magnetic field. When the plane of the armature is perpendicular to the magnetic field, θ = 0° or 180°, making cosθ = 1. Thus, the magnetic flux is maximum. However, the induced emf is given by Faraday’s Law as E = -dΦ/dt. Since flux is not changing at this instant, the induced emf is zero.
Thus, the correct answer is (d).
Important Questions from Electromagnetic Induction
In a pair of adjacent coils, for a change of current in one of the coils from 0 A to 10 A in 0.25 s, the magnetic flux in the adjacent coil changes by 15 Wb. The mutual inductance of the coils is:
A 50 Hz AC current of crest value 1 A flows through the primary of a transformer. If the mutual inductance between the primary and secondary is 0.5 H, the crest voltage induced in the secondary is:
A long solenoid of diameter 0.1 m has 2 × 104 turns per meter. At the center of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10π² Ω, then the total charge flowing through the coil during this time is:
Lower half of a convex lens is made opaque. Which of the following statements describes the image of the object placed in front of the lens?
A transformer has an efficiency of 80%. It works at 3 kW and 120 V. If the secondary voltage is 240 V, what will be the secondary current?
