What is the voltage across the plate of the capacitor if the capacitance is 5 µF and the charge stored is µC?

Question

A. 175 V

B. 7 V

C. 3.5 V

D. 0.14 V

Answer 1

Hi John!

Let's take a second to develop our physical intuition of what "capacitance" refers to, namely C=Q/V. In this way, the capacitance of a capacitor tells us how much charge it can store for a given voltage difference between the plates. Capacitance is a product of the geometry of a given capacitor (this is why cylindrical and rectangular capacitors have different values of capacitance!). To go an extra step further, we can add a dialectric between plates, which will reduce the net E field (and net voltage difference) between plates, allowing us to store a lot more charge for a given voltage!

Now we can return to the question at hand. Rearranging our equation, we get that V = Q/C. From here you can plug in values and hopefully arrive at the right answer!