DC circuits Physics Department, New York City College of Technology.
Published byModified over 5 years ago
Presentation on theme: "DC circuits Physics Department, New York City College of Technology."— Presentation transcript:
DC circuits Physics Department, New York City College of Technology
Key words Electromotive force (emf) Terminal voltage Resistors in parallel and in series Kirchhoff’s rules Junction rule Loop rule Capacitors in series and in parallel RC cuicuits
emf Electromotive force (emf) refers to the potential difference between the terminals of a source when no current flows out. Its symbol is .
Terminal voltage Terminal voltage is the potential difference between the terminals of a source when current flows, and is calculated as is the emf r is the internal resistance of the battery
Example #1 A 65-Ω resistor is connected to the terminals of a battery whose emf is 12V and whose internal resistance is 0.5Ω. Calculate (a) the current in the circuit, (b) the terminal voltage of the battery, and (c) the power dissipated in the resistor R and in the battery's internal resistance r.
Kirchhoff’s rules The junction rule: at any junction point, the sum of all currents entering the junction must equal the sum of all currents leaving the junction. It is based on the conservation of electric charge. The loop rule: the sum of the changes in potential around any closed path of a circuit must be zero. It is based on the conservation of energy.
Example #3 Calculate the currents I 1, I 2, and I 3.