Relation Between Current and Capacitance
Before learning about how to test a capacitor, it would be interesting first to find out regarding the mathematics involved during the testing process. Let’s read the brief explanation.
The charge Q on the capacitor may be expressed using the following formula:
Q = CV, where C is the capacitance and V is the supply voltage.
Now since the current involved during the process is given as:
I = Q × F, where F is the frequency of the square wave.
Replacing Q = CV in the above formula, we get:
I = CVF, clearly indicating that the capacitance C is directly proportional to the current I, provided, the frequency is constant.
Also, since the supply voltage is 9 volts, we finally have:
I = 9CF; this magnitude of current will reach the meter and will be responsible for the relevant readings.
Thus through calculations using the above formula a micro ammeter is initially calibrated suitably for a direct reading of the capacitor values in question.