Figure 1 shows a search coil positioned on the axis of an electromagnet, with the plane of the search coil perpendicular to the axis. A magnetic field is produced by a constant current in the electromagnet. Assume that the magnetic flux density inside the search coil is uniform.
The distance between the search coil and the end of the electromagnet is xxx. Figure 2 shows how the magnetic flux density BBB of the field varies with xxx.
The search coil has 300300300 turns and a cross-sectional area of 5.0×10−5 m25.0 \times 10^{-5} \text{ m}^25.0×10−5 m2.
The search coil is placed at x=0.080 mx = 0.080 \text{ m}x=0.080 m. Show that the magnetic flux linkage through the search coil is about 1.5×10−3 Wb1.5 \times 10^{-3} \text{ Wb}1.5×10−3 Wb.
The search coil is now moved at a constant speed of 1.2 m s−11.2 \text{ m s}^{-1}1.2 m s−1 along the axis so that xxx is increasing. An electromotive force (emf) is induced across the terminals of the search coil. Explain what happens to the value of the emf as the search coil moves.
The search coil passes through the position where x=0.12 mx = 0.12 \text{ m}x=0.12 m. Deduce whether the induced emf can exceed 15 mV15 \text{ mV}15 mV for values of xxx greater than 0.12 m0.12 \text{ m}0.12 m.