capacitors

Capacitors

• stores electrical charge
• consists of 2 metal plates close together seperated by an insulator
• a power souce flows into the negative plates to charge up the capacitor
• when the power source is removed the capacitor stays charged
• capacitance of the capacitor is measured in Farads (F)

Identifying capacitor size
by using this table i can work out the size of a capacitor by looking on the capacitor for the EIA code

μF	nF	pF	EIA code
0.00001	0.01	10	100
0.0001	0.1	100	101
0.001	1.0(1n0	1000	102
0.01	10	10000	103
0.1	100	100000	104
1.0	1000	100000	105
10	10000	1000000	106
100	100000	10000000	107

Expirement 1: compnents: 1 resistor, 1 capacitor, 1 switch



Circuit number	Capacitance (uF)	Resistance (Kohms)	Calculated time (ms)	Observed time (ms)
1	100	1	50	50
2	100	0.1	5	5
3	100	0.47	23.5	23.5
4	330	1	165	165

First i had to calculate the time the capacitor will take to charge up for each circuit (as above). To calculate the time first you have to put each unit in its base units (F,ohms,S) and then the formula is Capacitance x resistance x 5 e.g. 0.0001Fx1000ohmsx5=0.5seconds (answer to circuit 1) but because the calulated time has to be in ms you just convert it from seconds to milli seconds therefore the answer is 50ms.

observed time on an occiliscope circuit 1

circuit 2

circuit 3