Four students at a concert notice a balloon near the large speakers moving slightly towards, then away from the speaker during the low-frequency passages. The four students explain this phenomenon . Student A: The wave is a longitudinal wave because sound is made by regions of air being slightly more compressed followed by regions that are slightly less compressed.

Student B: The wave is a transverse wave because sound is made by regions of air being slightly more compressed followed by regions that are slightly less compressed.

Student C: The wave is a longitudinal wave because sound is made by regions of air moving perpendicular to the sound wave.

Student D: The wave is a transverse wave because sound is made by regions of air moving perpendicular to the sound wave

Which student correctly identifies the correct wave type and reason behind the balloons movement? (DOK 2)

A. Student B

B. Student A

C. Student D

D. Student C

the answer is b ) square root of 5

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2