As part of an advanced lab project, you design and construct a solenoid by wrapping a single layer of copper wire with a thin layer of varnish as insulation and with a diameter of 0.120 cm onto a plastic tube. The tube has a diameter of 12.0 cm, a length of 85.5 cm, and the coils are wrapped as tightly as possible. Determine the power that must be delivered to the solenoid in order to create a magnetic field of 9.60 mT at its center. The resistivity for copper is

Search coils and credit cards. one practical way to measure magnetic field strength uses a small, closely wound coil called a search coil. the coil is initially held with its plane perpendicular to a magnetic field. the coil is then either quickly rotated a quarter-turn about a diameter or quickly pulled out of the field. (a) derive the equation relating the total charge q that flows through a search coil to the magnetic-field magnitude b. the search coil has n turns, each with area a, and the flux through the coil is decreased from its initial maximum value to zero in a time ∆t. the resistance of the coil is r, and the total charge is q = i∆t, where i is the average current induced by the change in flux. (b) in a credit card reader, the magnetic strip on the back of a credit card is rapidly “swiped” past a coil within the reader. explain, using the same ideas that underlie the operation of a search coil, how the reader can decode the information stored in the pattern of magnetization on the strip. (c) is it necessary that the credit card be “swiped” through the reader at exactly the right speed? why or why not?

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.

The law of the conservation of momentum says that the total momentum of any closed and isolated system cannot