Near San Francisco, where the vertically downward component of the earth's magnetic eld is 6.2 x 10'5 T, a car is traveling forward at 34 m/s. The width of the car is 2.1 m. Find the emf induced between the two sides of the car. If positive charge accumulates on the driver's side, the enter the emf as a positive number. If negative charge accumulates on the driver's side, the enter the emf as a negative number. Number Units v Magnetic resonance imaging (MRI) is a medical technique for producing "pictures" of the interior of the body. The patient is placed within a strong magnetic field. One safety concern is what would happen to the positively and negatively charged particles in the body fluids if an equipment failure caused the magnetic field to be shut off suddenly. An induced emf could cause these particles to flow, producing an electric current within the body. Suppose the largest surface of the body through which flux passes has an area of 0.048 ma and a normal that is parallel to a magnetic field of 1.2 T. Determine the smallest time period during which the field can be allowed to vanish if the magnitude of the average induced emf is to be kept less than 0.012 V. B (out of screen) Number Units vAvacuum cleaner is plugged into a 120.0V socket and uses 3.6 A of current in normal operation when the back emf generated by the electric motor is 67.8 V. Find the coil resistance of the motor. Number I Units v In a television set the power needed to operate the picture tube comes from the secondary of a transformer. The primary of the transformer is connected to a 120V receptacle on a wall. The picture tube of the television set uses 114 W. and there is 5.5 mA of current in the secondary coil of the transformer to which the tube is connected. Find the turns ratio big/Np of the transformer. N's/Np: Number n Units v