S-31-2 A flat loop of wire consisting of a single turn of cross sectional area 8.0 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.50 T to 2.50 T in 1.0 s. What is the resulting induced current if the loop has a resistance of 2.0 . S-31-12 A magnetic field of 2.0 T exists in the region enclosed by a solenoid that has 500 turns and a diameter of 10 cm. Within what period of time must the field be reduced to zero if the average magnitude of the induced emf within the coil during this time interval is to be 10 kV? S-31-20 In the figure, the bar magnet is moved toward the loop. Is Va-Vb positive, negative or zero? Explain! Chapters 30 (021) Q28 A 2.0-T uniform magnetic field (in the x-y plane) makes an angle of 30 degrees with the yaxis. The magnetic flux through a 4.0-m**2 portion of the xz plane is: A1 6.9 Wb A2 4.0 Wb A3 3.0 Wb A4 8.0 Wb A5 12 Wb Q29 A 200-turn coil has a cross sectional area of 0.20 m**2 and a resistance of 20 ohms. The coil is placed in a magnetic field perpendicular to the plane of the coil. The magnitude of the magnetic field decreases from 1.6 milli-T to zero in 0.020 seconds. What is the current induced in the coil? A1 A2 A3 A4 A5 160 mA 3.20 mA 32.0 mA 16.0 mA 0.800 mA Q30 A square loop of wire lies in the plane of the page. A decreasing magnetic field is directed into the page. The induced current in the loop: A1 is clockwise. A2 is counterclockwise. A3 is zero. A4 depends upon whether or not B is decreasing at a constant rate A5 is clockwise in two of the loop sides and counterclockwise in the other two.