Combination of capacitors in parallel

Wire the circuit as shown in the following figure 2. for a resistance R = 3.8MΩ . and two capacitors of C1 =2 μF and C2=1 μF.

Note

Start counting the time using a stopwatch simultaneously when powering the circuit with a DC[1]voltage source E =8V.

Read the voltage at the capacitor terminals every 05 seconds and record the values in the following table

t(s)

00

05

10

15

20

25

30

35

40

45

50

55

Uc(V)

0

1.5

2.7

3.3

3.7

4.25

4.8

5.20

5.62

6.02

6.10

6.10

Method

a- On graph paper, plot the voltage Uc= f(t)

b- Plot the tangent to the origin point and determine the time constant, τ = RC; the abscissa of the point of intersection of this tangent with the limit voltage of the load.

c- From the time constant ensure the value of C.

d- Compare this value to the equivalent one of two capacitors in parallel

Capacitors in parallel

The equivalent one of two capacitors in parallel is given by

\[C_{eq}= C_{1} + C_{2}\]

Compare this value to the equivalent one of two capacitors in parallel

Extra

In this graph we found τ is 11.8s which is close to the calculated one τ = RC = 11.4s