Experiment no 4.pdf

Experiment no. 4 R L C series circuits Object: To study the ac characteristics of RLC circuits. Apparatus: 1- Dual beam oscilloscope. 2- Function generator. 3- Resistance box. 4- Capacitance box. 5- Inductance box. 6- Coaxial cable. 7- Connecting wires. Theory: A- Impedance: the impedance of a two t...

Experiment no. 4 R L C series circuits Object: To study the ac characteristics of RLC circuits. Apparatus: 1- Dual beam oscilloscope. 2- Function generator. 3- Resistance box. 4- Capacitance box. 5- Inductance box. 6- Coaxial cable. 7- Connecting wires. Theory: A- Impedance: the impedance of a two terminal network may be xpressed as: Z=v/I (ohms) Where z = complex impedance V= complex voltage I complex current The complex impedance is also expressed as: Z=r+jx in Cartesian form Z=zeiФ in polar form. A series RLC circuit is illustrated in fig.4.1. as obvious from the figure the effect of XL and XC are opposite. VL leads the current by 90° while VC lags the current by 90° thus the voltage across capacitor and inductor are out of phase by 180°. If the magnitude of these voltage are equal, they cancel each other and the total reactance in the circuit XL-XC=0 Fig.4.1: (a) circuit RLC in a series connection (b) phasor diagram of the RLC circuit The impedance shown in fig 4.2 of the circuit is Z=R+jXL-jXC Fig.4.2: impedance triangle of a series RLC circuit And the phase angle Ф shown in fig 4.2 is given by Ф=tan-1((VL-VC)/VR) =tan-1((XL-XC)/ R) If XL=XC the circuit is resistive XL>XC the circuit is inductive XL