# Physics - Recall for Chapter 22: Electric Fields

> Source: https://ollybritton.com/notes/a-level/physics/recall-questions/chapter-22-electric-fields/ · Updated: 2022-04-20 · Tags: physics, a-level, school, recall-questions

## 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??
$$
\text{NC}^{-1} \text{ or } \text{Vm}^{-1}
$$

##### 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??
$$
1\text{JC}^{-1}
$$

##### 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??
$$
\text{electric potential} \propto \frac{1}{\text{distance}}
$$

##### 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.

##### What is the relationship between electric potential energy $E_p$ and electric potential $V$??
$$
E_p = Vq
$$

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