# RC circuit voltage

1. Nov 4, 2007

### dizi100

Why the voltage across the capacitor can be measured by connecting a CRO across both the resistor and capacitor ?

actually,i have think of the phase difference and the overall resistance.Still,i can't find the answer.May I get some hints from you?

Last edited: Nov 4, 2007
2. Nov 4, 2007

### Staff: Mentor

How else would one propose to measure the voltage across a RC cirucit as a function of time, especially for short time constants?

Using a CRO (oscilloscope) is pretty standard. Of course, the impedance of the CRO needs to be high enough so as not to effect the measurement.

3. Nov 4, 2007

### dizi100

For ac voltage,voltage of the power supply equals voltage across both capacitor and resistor.
If i connect a CRO across both capacitor and resistor,i in fact measure the voltage of the power supply,right?
According to my lab manual,it states that i can mesure the voltage across the capacitor by connecting a CRO across the capacitor and resistor.
i really dont understand...