Agarage door opener has a component that stop the door from coming down if something is in the way. this component is made up of a laser light on one side and a receiver on the other. which best explains why this component works.

a) the receiver collects the laser light indicating that something is in the way.

b) any object blocking the path of the laser will reflect the beam into the reciever.

c) any object in its path changes the color of the laser before it gets to the reciever.

d) the laser light travels in a straight line towards the receiver, an object in the way blocks this straight line path.

the wavelength of a sound will give us information
a) how loud the sound will be
b) what produced the sound
c) the high or low pitch of the sound
d) the speed of sound

which statement about how sound travels is true?
a) the speed of sound is the same at all times.
b) the speed of sound depends on the material it travels through.
c) sound vibrations only move through a vacuum.
d) sound moves faster through insulators than conductors.

which statement about the electromagnetic spectrum is false?
a) there are wavelengths other than those of visible light in the spectrum.
b) microwaves have a longer wavelength than visible light.
c) the higher the energy of the wavelength, the more dangerous they are.
d) infrared light waves are visible.