Answer:
An electric current is a flow of particles (electrons) flowing through wires and components. It is the rate of flow of charge. If the electric charge flows through a conductor, we say that there is an electric current in the conductor. In the circuits using metallic wires, electrons constitute a flow of charges.
Z that is where both of the light rays intersect
The answer is the last option.
The mercury density (at liquid state) is
And we know that the pressure at the bottom of a column of fluid is given by (Stevin's law)
where
is the liquid density
g is the gravitational acceleration
h is the height of the column of fluid
The pressure at the bottom of the beaker is
, therefore we can re-arrange the previous equation to get the height of the column of mercury