Hi, I was trying to remember the formula for calculating the voltage across a given component within a circuit?

Hi @Jack,

Great question. You an normally solve this using V=IR, or P=IV depending on the information already given. You should also be prepared to calculate the resistance of the circuit, or a section of the circuit, using the resistance equations:

It is also possible to work out the voltage of a component based on the proportion of resistance. For example:

(This diagram was made using Falstad - a great circuit simulator you an use to make your own circuit diagrams and test your understanding.)

If the supply voltage is 5V, we could work out the voltage aross the 8 ohm component in this way:

Have a go at doing this for some more complex circuits as well. The collated exam questions on no brain too small might be useful. Let me know if you have any questions.