Physics A Level | Chapter 22: Coulomb’s law 22.1 Electric fields
LIVING IN A FIELD
The scientist in the Figure 22.1 is using a detector to measure the electric field produced by a mobile phone mast. People often worry that the electric field produced by a mobile phone transmitter may be harmful, but detailed studies have yet to show any evidence for this. If you hold a mobile phone close to your ear, the field strength will be far greater than that produced by a nearby mast.
With $5G$ being rolled out in various countries, what effect will this have on the local environment? Will it mean more masts and relay stations? Will copper cables be able to cope with the speed of the transmission of data needed to make $5G$ worthwhile? Will the investment needed to introduce $5G$ cause prices to rise for all customers?
In Chapter 21, we presented some fundamental ideas about electric fields:
- An electric field is a field of force and can be represented by field lines.
- The electric field strength at a point is the force per unit positive charge that acts on a stationary charge:
$field\,strength = \frac{{force}}{{charge}}$
$E = \frac{F}{Q}$
- There is a uniform field between charged parallel plates:
$field\,strength = \frac{{potential\,difference}}{{seperation}}$
$E = \frac{V}{d}$
In this chapter, we will extend these ideas to consider how electric fields arise from electric charges. We will also compare electric fields with gravitational fields (Chapter 17).