The u. s. has an alternating current frequency of 60 hz. china has an alternating current frequency of 50 hz. this means that

the number of times voltage cycles in a minute in the u. s. is greater than the number of times voltage cycles in china.

the peak voltage in china is smaller than the peak voltage in the united states.

the peak current in china is smaller than the peak current in the united states.

more than one of the above options is accurate.

Aballet student who learns with the of his instructor is demonstrating learning.

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?

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?