Answer: leftover radiation from the big bang
Microwave background radiation is a form of electromagnetic radiation that is present in the whole universe and completely fills it.
Its frequency belongs to the microwaves range and is one of the main demonstrations of the of the Big Bang theory model.
It is important to note the Big Bang occurred 400,000 years before the events related to the microwave cosmic radiation, this means the Big Bang occurred first.
Rainbows are caused by the dispersion of light, which itself consists of a combination of refraction and reflection of light around little droplets of water.
Choice C
Answer: 10.3m/s
Explanation:
In theory and for a constant velocity the physics expression states that:
Eq(1): distance = velocity times time <=> d = v*t for v=constant.
If we solve Eq (1) for the velocity (v) we obtain:
Eq(2): velocity = distance divided by time <=> v = d/t
Substituting the known values for t=15s and d=155m we get:
v = 155 / 15 <=> v = 10.3
It can be Strontium Iodide