13.6 Electric Generators and Back Emf

Design a current loop that, when rotated in a uniform magnetic field of strength 0.10 T, will produce an emf $\epsilon = \epsilon_{0} \text{sin} \omega t ,$ where $\epsilon_{0} = 110 \text{V}$ and $\omega = 120 \pi \text{rad}/\text{s} .$

A 50-turn rectangular coil with dimensions $0.15 \text{m} \times 0.40 \text{m}$ rotates in a uniform magnetic field of magnitude 0.75 T at 3600 rev/min. (a) Determine the emf induced in the coil as a function of time. (b) If the coil is connected to a $1000 - \Omega$ resistor, what is the power as a function of time required to keep the coil turning at 3600 rpm? (c) Answer part (b) if the coil is connected to a 2000-$\Omega$ resistor.

A flip coil is a relatively simple device used to measure a magnetic field. It consists of a circular coil of N turns wound with fine conducting wire. The coil is attached to a ballistic galvanometer, a device that measures the total charge that passes through it. The coil is placed in a magnetic field $\overset{\rightarrow}{B}$ such that its face is perpendicular to the field. It is then flipped through $180 ° ,$ and the total c…

A 120-V, series-wound motor has a field resistance of 80 $\Omega$ and an armature resistance of 10 $\Omega$. When it is operating at full speed, a back emf of 75 V is generated. (a) What is the initial current drawn by the motor? When the motor is operating at full speed, where are (b) the current drawn by the motor, (c) the power output of the source, (d) the power output of the motor, and (e) the power dissip…