Q3. a) Ferromagnetic materials are used widely in the construction of electrical machines, such as transformers, motors and generators. (i) Compare the properties of hard and soft ferromagnetic materials and sketch typical BH curves for each. (ii) When constructing magnetic circuits, why is a high permeability desirable? (iii) For a permanent magnet motor, why is a high coercivity important?

Q) If you wanted to shield your electronics from stray magnetic fields, what would you use for the box around your electronics. Explain why.

19. A square conducting loop of side a and resistance R passes through a region of space that has uniform magnetic field B into the page, as shown in the figure. Assume that the speed of the loop is constant throughout its motion. What is the magnitude and direction of the current in the loop: as it enters the magnetic field, a) b) while travelling inside the magnetic field, as it leaves the magnetic field. Provide your answer symbolically. a V Ø 8 Ø Top view Uniform magnetic field pointing into the page

3. DETAILS MY NOTES You are working during the summer at a company that builds theme parks. The company is designing an electromagnetic propulsion system for a new roller coaster. A model of a substructure of the device appears in the figure below. The rod is of length d = 1.00 m and mass m = 0.700 kg. The rod carries a current I = 100 A in the direction shown and rolls along the rails of length L = 15.0 m without slipping. The entire system of rod and rails is immersed in a uniform downward-directed magnetic field with magnitude 8 = 1.90 T. The electromagnetic force on the rod is parallel to the rails, causing the rod to roll to the right in the figure. When a full-scale device is produced, this rod will represent the axle of wheels on which the car and i on the grounds of the company. By projecting the rod from the rails in a horizontal direction from a height h = 1.80 m, the projection speed can be determined from how far from the ends of the rails the rod hits the ground. Your…