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

Answer:
2. west
Explanation:
Given an electron is moving vertically upward from ground.
Now Fleming right hand rule state that: make L shape with thumb and index finger then point middle finger perpendicular to index and thumb.Then index finger points in the direction of moving charge , middle finger points in the direction of the magnetic field and thumb points in the direction of the magnetic force.
According to Fleming right hand rule the direction of the magnetic that acts on the electron is west.
Answer:
4.62 s
Explanation:
We are given that
Initial angular speed,



Substitute the values






Hence, the wheel takes 4.62 s to come to rest.
Answer:
Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible.
Surface tension is caused by effects of intermolecular forces at liquid interface.
Surface tension increases as intermolecular forces increases.
Explanation:
- Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. It can also be seen as the energy required to increase the surface of a liquid by a unit amount.
- Surface tension is caused by the mediating effects of intermolecular forces at the liquid interfaces. Example in water, surface tension is caused by the mediating effect of the force between hydrogen and oxygen molecules. Liquids tends to reduce their surface area because of inward attarction of the liquid molecules.
- Surface tension increases as intermolecular forces increases. Also, surface tension decreases as intermolecular forces decreases.