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This topic is contained in pages $158-190$ of the textbook.

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The following relationship can be used in problems involving electrical force a system of point charges. This is known as Coulomb’s Law of electrical charges.

$$ F=\dfrac{Q_1Q_2}{4\pi\epsilon_or^2} $$

An electric field is the region that surrounds electrically charged particles in which a force is exerted on other electrically charged particles.

Electric fields exist around charged particles and between charged parallel plates; the field lines for standard arrangements of charged particles and plates are shown below. Field lines always point in the direction a positive charge would move if placed there. The closer the field lines the stronger the electric field.

Electric field strength, $E$ (measured in $N C^{-1}$), is the electrical force acting per unit positive charge in an electrical field.

$$ E=\dfrac{F}{Q} $$

The following relationship can be used in problems involving electric field strength and a system of point charges.

$$ E=\dfrac{Q}{4\pi\epsilon_or^2} $$

The electric field strength in problems involving a uniform electric field (e.g. between two plates) can be analysed using the following relationship.

$$ E=\dfrac{V}{d} $$

To find the vertical displacement of an electron upon leaving a uniform electric field the following relationship can be used, where $L$ is the length of the plates and $d$ is the distance between the plates.

$$ s_v=(\dfrac{Vq}{2mv^2d})L^2 $$

→ pages $163 - 164$ of textbook for derivation

The electrical potential, $V$ (measured in $V$), at a point is the work done in moving a unit positive charge from infinity to that point.