Radio waves: they are present in radios and also walkie-talkies
Answer:
Radio waves have a wavelength between and
While,
X rays have a wavelength between 1m and 10km.
=> It is one of the condition of diffraction that the obstacle (coming in the way) must be comparable with the size of the wavelength.
=> This shows, that radio waves have a wavelength which is comparable with the size of buildings and can really easily diffract through it
=> While, X-rays are big enough to diffract through the wall.
So, if an X-ray technician stands behind a wall during the use of her machine, she will remain safe.
Answer: D) Do rougher surfaces tend to create more friction than smooth surfaces?
Explanation:
Friction acts when either there is tendency or actually relative motion between two surfaces in contact. It depends upon the area of contact surface and roughness of the surfaces. More the area and roughness, more friction would be there. More friction would mean more force would be required to cause the relative motion between the two surfaces.
Here, sally and sue are changing the surface over ramp on which car moves. The surface area is same. The angle is same and the speed of the car is also same. So, the best research question to guide the girls' experiment would be D) Do rougher surfaces tend to create more friction than smooth surfaces?
Answer:
they become ionized and change to ions