Read the following passage and answer the questions below - Leaving Cert Physics - Question 13 - 2021

The size of the charge on one electron is $-1.6 \times 10^{-19}$ coulombs.

Electrons in an X-ray tube are produced through a process known as thermionic emission. This occurs at the hot cathode where electrons gain enough energy to escape the metal surface.

The mass of the drop can be calculated using the formula:

$m = \text{density} \times \text{volume} = 886 \, \text{kg/m}^3 \times 2.03 \times 10^{-7} \, \text{m}^3 = 1.8 \times 10^{-4} \, \text{kg}.$

The circuit symbol for a battery consists of two parallel lines, where one line is longer than the other. The long line represents the positive terminal and the short line represents the negative terminal:

+ |-------| -

An electric field is a region around a charged object where a force would be experienced by other charged objects. It is represented as a vector field, with direction indicating the force experienced by a positive charge and its magnitude represented by the density of field lines.

The electric field between two oppositely charged parallel plates is uniform. The field lines are straight and parallel, pointing from the positive plate to the negative plate:

|  + |-------------------| - |
|    |                   |   |
|    |-------------------|   |

When the drop is not moving up or down, the forces acting on it are the gravitational force pulling it downward and the electric force exerted by the electric field acting upward. These forces are balanced, leading to no net movement.