The answer 1 is
The best-known use of radio waves is for communication; television, cellphones and radios all receive radio waves and convert them to mechanical vibrations in the speaker to create sound waves that can be heard.Electromagnetic radiation is transmitted inwaves or particles at different wavelengths and frequencies.
the answer 2 is
Radio Waves: Instant Communication
Microwaves: Data and Heat
i think the answer number 3 is
It is all about wavelength versus tunnel diameter. The wavelength of GPS is about 20cm it would happily propagate in any normal tunnel if it could get in but the earth and other structures absorb it. AM radio (600kHz - 1500kHz) cannot propagate in any normal tunnel because the wavelength is too long (500m-200m) relative to the diameter, and thus gets reflected at the entrance. FM (100MHz ~ 3m) would propagate and it does for a while but then it suffers reflections
Answer:
Semi conductors are part of the fourth group in periodic table.
Explanation:
Periodic table is the arrangement of chemical elements on the basis of their atomic number. So all the elements with respective valence electrons are placed in thir respective groups. . All the elements with valence electrons four are placed in the fourth group .Semi conductors is the common name given to the elements of 4th group. These elements dont have the tendency to either donate or accept.
The group 3 elements have three electrons in their valence shell and hence have a tendency to donate. Whereas the group 5 elements having five valence electrons accept to satisfy thir octet. The semi conductors exist between 3rd and 5th groups exhibiting different properties according to the temperatures and excitations provided.
Answer:
B. the force of on the truck due to the collision is exactly equal to the force on the car.
Explanation:
At the time of collision between two objects of unequal or equal masses two forces emerge at the point of collision .They are called action and reaction force . According to third law of Newton , they are equal . So in the instant case of collision between car and truck , force on both of them will be equal.
Answer:
Hearing, Vision and Metabolism.
