Series and Parallel Resistances
Aim
To find out the effective of the multiple resistances connected in series and parallel.
Components
Name |
EDWin Components Used |
Description |
Number of components required |
| RES | RC05 | Resistor | 2 |
| VDC | VDC | Dc voltage source | 1 |
| GND | SPL0 | Ground | 1 |
Theory
- Series Resistances
Same current flows through each resistor
- The voltage drop across each resistor will be different.
- The applied voltage is equal to the sum of the voltage drops across individual resistor.
- Voltage drops are additive, resistances are additive
- Powers are additive
Total voltage applied,
Where I is the current through the circuit and R is the total resistance of the circuit.
Voltage drop across 
Voltage drop across 
which is the
equivalent series resistance.
- Parallel Resistances
When resistances are connected in parallel
- Same voltage acts across all resistors of the circuit
- Current flowing through each resistor varies.
- Branch currents are additive
- Conductances are additive
- Powers are additive.
Power,
Procedure
EDWinXP-> Schematic Editor: The circuit diagram is drawn by loading components from the library. Wiring and proper net assignment has been made. The values are assigned for relevant components. The series and parallel resistance circuit diagrams in the Mixed mode simulator is shown below.
EDWinXP -> Mixed Mode Simulator: The circuit is preprocessed. The desired test points and waveform markers are placed. The Transient Analysis parameters have been set. The Transient Analysis is executed. The test points display the values of the current through the resistors as shown.
The variation of current through the two resistors with respect to variation in voltage is obtained by performing DC Sweep Analysis on both series and parallel resistance circuits. To perform DC Sweep Analysis a current waveform marker is placed. The sweep parameter (voltage) for input source is set in the Analysis window. The applied voltage is swept from an initial value of 0 to final value of 10V in steps of 100mV. The DC Sweep Analysis is executed and the corresponding waveforms are observed in the Waveform Viewer.
Result
The output waveform may be observed in the waveform viewer. The output waveforms of DC Sweep Analysis for series and parallel resistance circuits are shown below. From the graphs it is evident that the effective of the two similar resistances when connected in series will be greater compared to the case when they are connected in parallel.
