Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CR circuit - schoolphysics
Document related concepts
Integrated circuit wikipedia , lookup
Distributed element filter wikipedia , lookup
Negative resistance wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Spark-gap transmitter wikipedia , lookup
Crystal radio wikipedia , lookup
Integrating ADC wikipedia , lookup
Regenerative circuit wikipedia , lookup
Index of electronics articles wikipedia , lookup
Josephson voltage standard wikipedia , lookup
Power electronics wikipedia , lookup
Standing wave ratio wikipedia , lookup
Electrical ballast wikipedia , lookup
Schmitt trigger wikipedia , lookup
Voltage regulator wikipedia , lookup
Operational amplifier wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Valve RF amplifier wikipedia , lookup
Current source wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Two-port network wikipedia , lookup
Surge protector wikipedia , lookup
Power MOSFET wikipedia , lookup
Zobel network wikipedia , lookup
Opto-isolator wikipedia , lookup
Current mirror wikipedia , lookup
Rectiverter wikipedia , lookup
Transcript
The C-R (capacitance-resistance) circuit The circuit shown in Figure 1 contains both resistance and capacitance, and therefore both the component and the frequency of the supply voltage affect the current in the circuit. The a.c. resistance of such a circuit is known as the impedance of the circuit and is denoted by the symbol Z. Impedance is measured in ohms. We will now deduce the impedance of the circuit using the vector treatment. Consider the voltages round the circuit. The supply voltage will be denoted by Vo and the voltages across the resistor and capacitor by V R,0 and V C,0 respectively. We know that for a resistor the current and voltage are In phase, while for a capacitor the current leads the voltage by 90o; vR,O therefore leads vC,O by 90o, as shown in the vector diagram in Figure 2. C R vR vC Figure 1 vR0 vR0 t vR Time (t) = t Time (t) = 0 v0 vC0 v0 v vC Figure 2 vC0 The resultant voltage v0 is given by vo2 = vR,O 2 + vC,O 2 = i02R2 + i02X2C Therefore the current in the circuit is given by: io = vo √[XC2 + R2] and the impedance Z by: Z = v0/i0 = √[XC2 + R2] = √[1/2C2 + R2] Voltage vC0 vR vR0 Time vC Figure 3 The angle that the resultant vector makes with V is known as the phase angle of the voltage. You can see from Figure 3 that tan vC0/vR0 = -1/CR 1
