### EXAM GUIDELINES P1

## Electrostatics

**(This section must be read in conjunction with the CAPS, p. 84–85.) **
### Coulomb's law

**State** Coulomb's law:

The magnitude of the electrostatic force exerted by one point
charge (Q_{1} ) on another point charge (Q_{2} ) is directly proportional to the product of the
magnitudes of the charges and inversely proportional to the square of the distance (r)
between them:
**Solve** problems using the equation:

for charges in one dimension (1D)

(restrict to three charges).
**Solve** problems using the equation:

for charges in two dimensions (2D)

– for three charges in a right-angled formation

(limit to charges at the 'vertices of a right- angled triangle').

### Electric field

**Describe an ** **electric field** as a region of space in which an electric charge experiences a
force. The direction of the electric field at a point is the direction that a positive test
charge would move if placed at that point.
**Draw electric field patterns** for the following configurations:
- A single point charge
- Two point charges (one negative, one positive OR both positive OR both
negative)
- A charged sphere
**NOTE:**

Restrict to situations in which the charges are identical in magnitude.

**Define** the *electric field at a point*:

The electric field at a point is the electrostatic force
experienced per unit positive charge placed at that point.

In symbols:

**Solve** problems using the equation:

**Calculate** the electric field at a point due to a number of point charges, using the equation:

to determine the contribution to the field due to each charge.

Restrict
to three charges in a straight line.