Capacitors

Capacitors are electronic devices used to store electrical charge and prevent voltage spike. The negative plate provides a form of reservoir into which electron can flow and this stores any excess of voltage. It is measured in Farad.

The capacitor will discharge almost instantly, but to charge up need a bit time. However majority of it charge capacity will be charged up very quickly. As capacitor is getting more charged up it becomes hard because the capacity is nearly filled up with charges, this is why it take even longer to charge this remaining portion.

Time needed for a capacitor to get fully charge can be calculate with the formula below

T = 5RC

T is the time takes to fully charge a capacitor

5 is a constant

R is the resistance that connect in series with a capacitor to control the charging rate

C is the capacitance of the capacitor

In this lab we want to fully charge a 16V 330uF capacitor in 180secs

Above formula is used to calculate the resistor needed to control the charge up time

R = T / (5C)

T = 180s

C= 0.0033F

R=180/5(0.0033) = 10kohm

I connect this capacitor in series with 10kohm resistor in series with a supply voltage of 13.31V. I discharged the capacitor by connecting its leads with a jumper wire then removed the jumper wire to let it charge up and recorded the following voltages with 10 seconds interval for 180 seconds:

10s     7V	20 s     12V	30s  13.25V	40s   13.2 V	50s   13.2 V	60 s  13.29 V
70s  13.30V	80s  13.30 V	90s  13.30 V	100s 13.30 V	110s 13.30 V	120 s 13.30 V
130s 13.30V	140s 13.30 V	150s 13.30V	160s 13.30V	170s 13.30 V	180 s 13.31 V

This shows this charging characteristic of a capacitor, it charges up very quickly in the begin and getting slower and slower to towards the end.