Answer:
ok what do you need to know about ''campaign against crime''?
Explanation:
I'm not really sure what specific answer they're looking for, but if it's an open-ended question, then let's think about it this way...
A light year, is the distance it takes for light to travel in a year. If an object is 50,000 light years away, then by the time the light travels to us, 50,000 years has passed. We are looking at a 50,000 year old image of that object. (ignoring gravity and spatial expansion fun stuffs)
Answer:
in a vacuum
Explanation:
Electromagnetic waves are waves consisting of oscillations of electric and magnetic fields along a plane perpendicular to the direction of propagation of the wave (transverse waves)
Electromagnetic waves are the only waves being able to travel in a vacuum, since they do not need a medium to propagate.
In a vacuum, all electromagnetic waves travel at the same speed, called speed of light, whose value is:

The speed of the waves is actually reduced when they enter a medium, according to

where n is the refractive index of the medium.
Electromagnetic waves are also classified into 7 different types according to their wavelength. From shortest to longest wavelength, we have:
Gamma rays
X-rays
Ultraviolet
Visible light
Infrared
Microwaves
Radio waves