According to the doppler effect, which statement is true about a sound as it approaches you and then moves away. a) as the source approaches you, the waves are compressed so that the pitch of the noise increases. b) the pitch of the sound remains the same the entire time, regardless of the direction of the source. c) as the source moves away from you the sound wave are compressed so the pitch of the noise increases. d) as the source approaches you, the sound waves are stretched relative to the individual so the pitch of the noise decreases.

Chapter 23, problem 075 the figure shows a geiger counter, a device used to detect ionizing radiation (radiation that causes ionization of atoms). the counter consists of a thin, positively charged central wire surrounded by a concentric, circular, conducting cylindrical shell with an equal negative charge. thus, a strong radial electric field is set up inside the shell. the shell contains a low-pressure inert gas. a particle of radiation entering the device through the shell wall ionizes a few of the gas atoms. the resulting free electrons (e) are drawn to the positive wire. however, the electric field is so intense that, between collisions with gas atoms, the free electrons gain energy sufficient to ionize these atoms also. more free electrons are thereby created, and the process is repeated until the electrons reach the wire. the resulting "avalanche" of electrons is collected by the wire, generating a signal that is used to record the passage of the original particle of radiation. suppose the radius of the central wire is 24 âµm, the inner radius of the shell 2.3 cm, and the length of the shell 14 cm. if the electric field at the shell's inner wall is 2.8 ă— 104 n/c, what is the total positive charge on the central wire?

Write the correct abbreviation for each metric unit

When the magnetic domains in a material can be aligned, but eventually drift out of alignment, the material is