# Different terms for the same thing(Expansion – tell me more)

### Confused?–try this

Read this if you are confused about the use of many different terms.

Voltage and potential difference and potential drop and p.d.

Very often, the voltage across a circuit component, such as a bulb, is referred to as a potential difference (a p.d.).

Teacher: So, if I just take the reading of the voltmeter, it's 2.5 volt. The p.d. across the bulb is 2.5 volt.

Sometimes you might hear people talk about the voltage across the bulb, at other times about the potential difference across the bulb and sometimes about the potential drop or p.d. On first hearing this, it can be confusing! However, the diagrams we use show that the voltage is a measure of the difference in potential energy per coulomb as charge passes through a circuit component. Hence the use of the terms potential difference or potential drop. At this stage is probably simpler for pupils just to use voltage.

There is more on the reasons to prefer thinking about potential difference later in this episode and much more in the SPT: Electricity and energy topic.