An a.c. generator consisting of a coil of 100 turns and cross-sectional area of 3 m2 is rotating at a constant angular speed of 60 rad s–1 in a uniform magnetic field of 0.04 T. The resistance of the coil is 500 . Calculate maximum current drawn from the generator, and power dissipation in the coil. From where does the power come?
The maximum emf induced in the coil is given by
The maximum current induced in the coil, which can be drawn from the generator is
The power dissipated as heat in the resistance of the coil is
= 518.4 W.
The induced current causes a torque on the coil opposing its rotation (Lenz’s law). An external agent (a rotor) does work to produce a counter torque to make the coil rotate uniformly. This work is the source of power dissipated in the coil.
The instantaneous current in a circuit is given by I = 2cos (u4t + Ï•) ampere. The r.m.s value of the current is
A (100w, 200v) bulb is connected to a 160v supply. The power consumption would be
The induced emf in armature will be zero, when armature is rotated at an angle
An a.c. source is of 120 volt , 60Hz the value of the voltage after 1/360 sec from the start will be
Resonance frequency of a circuit is f if the capacitance is made 4 times the initial value , then the resonance frequency will become
In and A.C. circuit , minimum voltage of 423 Volt. Its effective voltage is
The average power dissipation in a pure capacitor in A.C. circuit is
A 100-turn rectangular coil of size 0.20 m × 0.10 m rotates in a magnetic field of 0.003 Wb m–2 with a frequency of 1200 rpm about an axis normal to the field. Find the maximum value of the induced emf.
An a.c. generator consists of a coil of 50 turns and area 2.5 m2 rotating at an angular speed of 60 rad s–1 in a uniform magnetic field of 0.30 T. The resistance of the circuit including that of the coil is 500 . Find the maximum current drawn from the generator.
In a dynamo, a coil of area 0.2 m2 and having 100 turns rotates in a magnetic field of 0.1 Wb m–2 with an angular velocity of 100 rad s–1. The output terminals are connected through a resistance of . Calculate the torque , as a function of time t, required to keep the coil rotating.