Read this if you are confused about the use of many different terms.
potential difference and
potential drop and
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
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.