Answer:
A. 
B. 
C. 
Explanation:
The capacitance of a capacitor is its ability to store charges. For parallel-plate capacitors, this ability depends the material between the plates, the common plate area and the plate separation. The relationship is

is the capacitance,
is the common plate area,
is the plate separation and
is the permittivity of the material between the plates.
For air or free space,
is
called the permittivity of free space. In general,
where
is the relative permittivity or dielectric constant of the material between the plates. It is a factor that determines the strength of the material compared to air. In fact, for air or vacuum,
.
The energy stored in a capacitor is the average of the product of its charge and voltage.

Its charge,
, is related to its capacitance by
(this is the electrical definition of capacitance, a ratio of the charge to its voltage; the previous formula is the geometric definition). Substituting this in the formula for
,

A. Substituting for
in
,

B. When the distance is
,


C. When the distance is restored but with a dielectric material of dielectric constant,
, inserted, we have

Clarify what you mean by ratios?
Answer:
h = 16.67m
Explanation:
If the kinetic energy of the cylinder is 510J:


Where the inertia is given by:

Replacing this value:

Speed of the block will therefore be:

By conservation of energy:
Eo = Ef
Eo = 0

So,

Solving for h we get:
h=16.67m
Explanation:
Given that,
Wavelength of the light, 
Work function of sodium, 
The kinetic energy of the ejected electron in terms of work function is given by :

The formula of kinetic energy is given by :

Hence, this is the required solution.
True since coulomb's law states that There is electric force between like charges or opposite charges. The negative sign only shows the nature of the force.
<h3>What is the coulombs law ?</h3>
coulombs formula is given by

Now it states that if two charged particles are separated by the distance r and having same or opposite charge will attract or repel each other.
The intensity of the force depend upon the distance and the nature of the charge.
Hence coulomb's law states that There is electric force between like charges or opposite charges. The negative sign only shows the nature of the force.
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