Electromagnetism 2

 1 A 0.40 kg metal slider is sitting on smooth conducting rails as shown below. What is the magnitude and direction of the acceleration of the slider? (Ignore friction.) 2 A 0.20 m long solenoid has 750 turns of copper wire and the magnetic field near its centre is measured to be 3.0 x 10-2 T. What is the current flowing through the solenoid? A. 1.6 A B. 6.4 A C. 32 A D. 160 A 3 A 0.050 m long conducting wire is moved through a 1.5 T magnetic field as shown below. What is the magnitude of the emf generated between its ends, and in what direction do the electrons in the conductor initially move? 4 The circular loop of wire shown below has an area of 0. 40 m2 and is in a 0.60 T magnetic field. This field is increased to 1.40 T in 0.25 s. Determine the emf produced in the loop and the direction of current. 5 The load on an electric motor is gradually increased. Which one of the following quantities decreases? (Input voltage remains constant.) A. current B. back emf C. armature resistance D. heat produced by armature 6 The graph below shows how the emf produced by an ac generator varies with time. At which point in time is the rate of flux change in the generator the greatest? A. a B. b C. c D. d 7 A solid conductor travels at 150 m/s across a uniform 0.045 T magnetic field. Which side is positively charged and what is the emf across this block? 8 A 120 V dc motor has an armature resistance of 5.0 W and draws 6.0 A when it is operating normally. What is the starting current of the motor and the back emf when it is operating? 9 The diagram shows a bar magnet falling through an aluminum pipe. Electric currents are induced in the pipe immediately above and below the falling magnet. In which direction do these currents flow? 10 The diagram shows a 0.010 kg metal rod resting on two long horizontal frictionless rails which remain 0.40 m apart. The circuit has a resistance of 3.0 W and is located in a uniform 0.20 T magnetic field. Find the initial acceleration and maximum velocity for the rod.

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