Voltage and current capacitor

Kazakh-British Technical University

Faculty of Information Technologies

Foundations of Electrical Engineering II

 

Report for Laboratory work #4

 

Prepared by:

2^nd year student of FIT

Zhaksylyk Elzhas

ID: 11BD02146

Teacher:Hasan Mahmud

 

Almaty 2013

Sinusoid current circuit (AC) with capacitor

Voltage and current capacitor

Theory:

The capacitor is different from the resistor in several ways. First, it consumes no real power. In DC circuits after the initial charge or discharge no current can flow, in AC circuits a current flows all the time into and out of the capacitor, depending on the impedance in the circuit. This is similar to the resistance in DC circuits, except that the impedance has 2 parts; the resistance included in the circuit, and also the reactance of the capacitor, which depends not only on the size of the capacitor, but also on the frequency of the applied voltage. If we apply the above formula to a AC voltage:

),

we get for the current a 90° phase shift: .

In an AC circuit, current leads voltage by a quarter phase or 90 degrees.

Phase shift:

Figure 1.1

 

 

Figure 1.2

 

 

1.2 Experimental part:

· Collect circuit according to the diagram (Figure 1.2), and connect the regulated source

sinusoidal voltage U = 5 V and f = 1 kHz.

· Connect virtual devices A1(ammeter), V0(voltmeter) and oscilloscope

· Enter data from devices to the table bellow(Table 1.2)

· Draw graph(Figure 1.3) with data on the table

Table 1.2

Time t, ms	Current Ic, mA	Voltage Vc, V	Power P=Vc*Ic, mW
		4,29
0,2	17,14	4,72	81,09
0,4	28,61	3,31	94,74
0,6	30,58	0,59	18,19
0,8	22,42	-2,35	-52,81
	6,82	-4,38	-29,89
1,2	-11,03	-4,68	51,75
1,4	-25,24	-3,15	79,66
1,6	-31,07	-0,38	11,99
1,8	-26,60	2,53	-67,46
	-13,31	4,46	-59,42

Figure 1.3

 

2.1 Task:

Display the virtual oscilloscope curves of current and voltage of various capacitors 0.22, 0.47, 1 uF. Determine the appropriate reactive resistance formulas:

, .