A toroid is a solenoid in the shape of a donut (Fig. 20-60). Use Ampére's law along the circular paths, shown dashed in Fig 20-60a, to determine that the magnetic field a) inside the toroid is B= u0 NI/2piR where N is the total number of turns and...
b)outside the toroid is B=0
c)If not, how does it vary?

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.

What quantity do units represent in value

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.