1. an electromagnetic wave in a vacuum has a wavelength of 0.07 m. what is its frequency?
f = 3.0 • 108 m/s
f = 4.3 • 109 hz
f = 3.0 • 109 hz
f = 4.3 • 108 m/s
2. which of the following occurs as light travels farther from its source?
far from the source, photons come together in a small area.
the intensity of light increases as photons move away from the source.
the source gives off less light as photons move away from it.
far from the source, photons spread over a larger area.
3. infrared rays have a shorter wavelength than
ultraviolet rays.
x-rays.
radio

1) We know that the speed of electromagnetic waves is 3 x 10⁸ m/s
v = fλ
f = v/λ
f = (3 x 10⁸)/0.07
f = 4.3 x 10⁹ Hz

2) Far from the source, photons spread over a larger area. This is why the intensity of light decreases as we get further from its source.

3) A shorter wavelength means a higher energy. On the electromagnetic spectrum, the less energetic waves than Infrared wavers are Radio waves.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j