Q. Presume the needle moves 7.5 mm from its highest to its lowest position and it makes 26 stitches in 9.1 s. What is the highest needle speed?
Q. A 115 turn square wire coil of area 0.040 m2 rotates about a vertical axis at 1750 rev/min, as indicated in the figure below. The horizontal component of Earth's magnetic field at the location of the loop is 2.0 10-5 T. Estimate the highest emf induced in the coil by Earth's field.