If a substance besides water is changed from a gas to a liquid and then to a solid, what happens to the particles?

they get closer together
they get farther apart
they get closer together, then farther apart
they get farther apart, then closer together

1) Option D is correct.

The electric field inside a conductor is always zero.

2) Option A is correct.

The charge density inside the conductor is 0.

3) Charge density on the surface of the conductor at that point = η = -E ε₀

Explanation:

1) The electric field is zero inside a conductor. Any excess charge resides entirely on the surface or surfaces of a conductor.

Assuming the net electric field wasn't zero, current would flow inside the conductor and this would build up charges on the exterior of the conductor. These charges would oppose the field, ultimately (in a few nanoseconds for a metal) canceling the field to zero.

2) Since there are no charges inside a conductor (they all reside on the surface), it is logical that the charge density inside the conductor is also 0.

3) Surface Charge density = η = (q/A)

But electric field is given as

E = (-q/2πε₀r²)

q = -E (2πε₀r²)

η = (q/A) = -E (2πε₀r²)/A

For an elemental point on the surface,

A = 2πrl = 2πr²

So,

η = -E ε₀

Hope this Helps!!!