120 likes | 275 Views
Engineering Fundamentals and Problem Solving, 6e. Chapter 17 Electrical Circuits. Chapter Objectives. Compute the equivalent resistance of resistors in series and in parallel Apply Ohm’s law to a resistive circuit
E N D
Engineering Fundamentals and Problem Solving, 6e Chapter 17 Electrical Circuits
Chapter Objectives Compute the equivalent resistance of resistors in series and in parallel Apply Ohm’s law to a resistive circuit Determine the power provided to a DC circuit and the power used by circuit components Use Kirchhoff’s laws to solve resistive networks Utilize mesh currents to solve resistive networks
Ohm’s Law Potential = Current X Resistance Where V =Potential in volts R =Resistance in ohms I = Current in amperes
Resistors in Series V1 V2 V3 VT
Kirchhoff’s Laws Kirchoff’s voltage law • “The algebraic sum of all the voltages (potential drops) around any closed loop in a network equals zero.” Vdrops= 0 Kirchoff’s current law • “The algebraic sum of all of the currents coming into a node (junction) in a network must be zero.” Inode= 0
Circuit Example 17.7 Given the following circuit, determine the currents Ix, Iy, and Iz.
Circuit Example cont’d From Kirchhoff’s current law at point A Iy= Ix+ Iz From Kirchhoff’s voltage law around left loop - Iy(2) + 14 – Ix(4) = 0 Around right loop - Iy(2) + 12 – Iz(6) = 0 Results in: Ix = 2A, Iy = 3A, Iz = 1A
Mesh Currents • A node is a specific point or location within a circuit where two or more components are connected. • A branch is a path that connects two nodes. • A mesh is a loop that does not contain any other loops within itself. • Mesh currents • Exist only in the perimeter of the mesh • Selected clockwise for each mesh • Travel all the way around the mesh
Mesh Current Example V1 V2 Write the mesh current equations for this circuit. V1 – IaR1 – (Ia – Ib)R3 = 0 -V2 – (Ib – Ia)R3 – IaR2 = 0