Chapter 1: Introduction and DC Circuit MOHD ASRI BIN JUSOH

Chapter 1.3: Series DC Circuit, Kirchhoff Voltage Law, Voltage Divider Rule, Notation

Introduction The battery has ability to cause charge to flow through the circuit. The +ve terminal attracts the electron through the wire at the same rate. If we consider the wire to be an ideal conductor, the potential difference V across the resistor equal the applied voltage of battery

Introduction (Cont…) The current is limited only by resistor R. The higher R, The less I The lower R, The higher I The direction of conventional current flow (Iconventional) is opposite to that of electron flow (Ielectron)

Series Resistors Two elements are in series if: - they have only one terminal in common. - the common point between the two element is not connected to another current-carrying element.

Series Resistors (Cont…) The total resistance of a series configuration is the sum of the resistance level. The more resistor we add in series, the greater the resistance (no matter what their value)

Series Resistors (Cont…) When series resistor have the same value: RT = total value of resistor (Ω) N = number of resistor in series R = the value of resistance

Series Resistors (Cont…) Find RT

Series Circuit A circuit is any combination of elements that will result in a continues flow of charge, or current, through the configuration. The direction of conventional current in a series dc circuit is such that it leaved the +ve terminal of the supply and return to the –ve terminal.

Series Circuit (Cont…) The current is the same at every point in a series circuit. Voltage in series circuit is the total voltage (VT) of each element circuit.

Series Circuit (Cont…) Since E is fixed, the magnitude of the source current will be totally dependent on the magnitude of RT

Series Circuit (Cont…)

Series Circuit (Cont…) Find RT, IS, V1, V2 and V3

Series Circuit (Cont…) Find R1, and E

Series Circuit (Cont…) Voltage measurement

Series Circuit (Cont…) Current measurement

Series Circuit (Cont…) Power distribution

Series Circuit (Cont…) Find RT, IS, V1, V2, V3, PE, P1, P2 and P3

Series Circuit (Cont…) Voltage source

Kirchhoff’s Law Gustav Robert Kirchhoff Introduced 2 laws: - Kirchhoff Voltage Law (KVL) - Kirchhoff Current Law (KCL)

Kirchhoff’s Voltage Law (KVL) KVL states that the algebraic sum of the potential rises and drops around a closed path (closed loop) is zero (0) The sum of voltage applied is equal to the sum of load voltages

Kirchhoff’s Voltage Law (KVL) (Cont…) Find unknown voltage:

Kirchhoff’s Voltage Law (KVL) (Cont…) Find V1 and V2:

Kirchhoff’s Voltage Law (KVL) (Cont…) Find V2, I2, R1 and R2:

Voltage Divider Rule The voltage across series resistive elements will divide as the magnitude of the resistance levels.

Voltage Divider Rule (Cont…) Find V1: Find V1 and V3:

Notation Voltage source and ground

Notation (Cont…) Replace the notation for a –ve dc supply with the standard supply.

Notation (Cont…) Double-subscript notation - the double-subscript notation Vab specifies point a as the higher potential. If this is not the case, a negative sign must be associated with the magnitude of Vab. The voltage Vab is the voltage at a point a with respect to point b.

Notation (Cont…) Single-subscript notation - the single-subscript notation Va specifies the voltage at point a with respect to ground (0 V). - if the voltage is less than 0 V, a –ve sign must be associated with the magnitude of Va

Notation (Cont…) Find Vab: Find Va:

Notation (Cont…) Find Vb, Vc and Vac:

Notation (Cont…) Find Vab, Vcb and Vc: