Answer:
low risk for tissue damage
uses radio waves
the last three are not correct
:)
Answer:

Explanation:
P = Power = 50 kW
n = Number of photons per second
h = Planck's constant = 
= Frequency = 781 kHz
r = Distance at which the photon intensity is i = 1 photon/m²
Power is given by

Photon intensity is given by

The distance is 
Answer:
1000 Hz
Explanation:
<em>The frequency would be 1000 Hz.</em>
The frequency, wavelength, and speed of a wave are related by the equation:
<em>v = fλ ..................(1)</em>
where v = speed of the wave, f = frequency of the wave, and λ = wavelength of the wave.
Making f the subject of the formula:
<em>f = v/λ.........................(2)</em>
Also, speed (v) = distance/time.
From the question, distance = 900 m, time = 3.0 s
Hence, v = 900/3.0 = 300 m/s
Substitute v = 300 and λ = 0.3 into equation (2):
f = 300/0.3 = 1000 Hz
The correct answer to the question is False i.e the tendency of an object in motion to remain in motion is not called the orbital speed.
EXPLANATION:
Before going to answer this question, first we have to understand Newton's first laws of motion.
As per Newton's first laws of motion, every body continues to be in state of rest or of uniform motion in a straight line unless and until it is compelled by some external unbalanced forces.
Hence, as long as no unbalanced force is acting on a moving object, it will be in motion. This tendency of a moving object to be in motion is called inertia of motion of the body.
Inertia of motion is the property of the body by virtue of which a moving body always tries to be in motion.
Hence, the tendency of an object in motion to remain in motion is not called as the orbital speed.