# Physics - Recall for Chapter 22; Electric Fields

## Flashcards

### 2022-04-20

What is an electric field?

A region of space where a charge will experience an electrostatic force.

What is electric field strength?

The force per unit charge on a positive test charge placed at a point in a field.

What are the two different units of electric field strength?

What does the direction of an electric field line show?

The direction of the force exerted on a positive test charge.

What does the spacing of electric field lines show?

Field strength.

What is a test charge?

A positive unit charge.

When is the equation $E = \frac{V}{d}$ used?

To find the uniform field strength between two parallel plates.

What is Coulomb’s law in words?

The force between two point charges is:

- Proportional to the product of the two charges.
- Inversely proportional to the square of their separation.

What is electric potential difference?

The work done per unit positive charge in moving between two points.

What is the electric potential of a point?

The work done per unit positive charge to move from infinity to that point.

What is a Volt?

What is the relationship between the electrostatic force between two point charges and their separation distance?

It is inversely proportional to the square of separation.

What is the relationship between electric potential and distance from a point charge?

What is a uniform electric field?

A region of space in which the electric field strength is the same at all points.

What is a radial field?

An electric field generated by a point charge.

What sort of electric fields are characterised by the inverse square law?

Radial field.

What is a neutral point in an electric field?

A point at which the resultant field strength is zero.

Is electric field strength a vector or a scalar quantity?

Vector.

Is electric potential a vector or a scalar quantity?

Scalar.

What are two similarities between electric and gravitational fields?

- Both obey the inverse square law for field strength.
- Both have infinite range.

What are two differences between electric and gravitational fields?

- Gravitational fields act on masses, electric fields act on charges
- Gravitational fields are always attractive, whereas electric potential is always negative

## \[V = \frac{Q}{4\pi \epsilon _ 0 r}\]
When is this equation used?

To find the potential in a radial field.

## \[C = 4 \pi \epsilon _ 0 r\]
What is this equation used for?

To calculate the capacitance of an isolated sphere.