Answer:
The wavelength can always be determined by measuring the distance between any two corresponding points on adjacent waves. In the case of a longitudinal wave, a wavelength measurement is made by measuring the distance from a compression to the next compression or from a rarefaction to the next rarefaction.
Explanation:
Yah isnt that obvious? Gasses mix everywhere in all proportions.
Well, since you only want direction, ignore the numbers. Use the right hand rule.
Current (pointer finger) points west (left).
Magnetic field (middle finger) points south (towards you).
Force (thumb) then points up (away from the earth)
You draw a straight line from the start point to the end point. It doesn't matter what route was actually followed for the trip.
Read each statement, one at a time, and form the picture in your mind.
<em>Statement #1</em> should make you feel all warm and fuzzy inside.
Statements #2, #3, and #4 should make your red flag wave on the inside, and should make you giggle on the outside when you realize how absurd each of those is.