To measure the height of the cloud cover at an airport, a worker shines a spotlight upward at an angle 75 from the horizontal. an observer 600 m away measures the angle of elevation to the spot of light to be 45. find the height h of the cloud cover.

a longitudinal wave moves energy that is to the direction of the wave’s movement. - true

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

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

360seconds i 1 hr