Answer: the correct answer is (B) He did not know that interstellar dust made it hard from him to see a large part of the Milky Way's disk.
Explanation:
We live in a dusty Galaxy. Because interstellar dust absorbs the light from stars, Herschel could see only those stars within about 6000 light-years of the Sun.
Answer:
The magnitude of the electric force between the to protons will be 57.536 N.
Explanation:
We can use Coulomb's law to find out the force, in scalar form, will be:
.
Now, making the substitutions
,
,
,
we can find:
.
.
Not so big for everyday life, but enormous for subatomic particles.
Answer:

Explanation:
= Avogadro's number = 
e = Charge of electron = 
k = Coulomb constant = 
Z = Atomic number of water = 18
M = Molar mass of water = 0.018 kg/mol
m = Mass of person
The charge is given by

Total number of protons and electrons in each sphere




Electrical force is given by

The electrostatic force of attraction between them is 