Which of these statements best explains why p waves arrive earlier than s waves at the seismic station?

a. s waves are generated after p waves arrive at the surface
b. s waves make longer lines on the seismogram than p waves
c. p waves are created first and s waves originate from p waves when they are reflected by solid rocks
d. p waves move straight through all medium and s waves move only through solids in a curvy motion

Aresearcher plans to conduct a test of hypotheses at the 1% significance level. she designs her study to have a power of 0.90 at a particular alternative value of the parameter of interest. the probability that the researcher will commit a type ii error for the particular alternative value of the parameter at which she computed the power is: a. 0.90. b. 0.01. c. 0.10. d. equal to 1

In a voltaic cell, electrons flow from the (positive/negative) to the (positive/negative) terminal.

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?