Power of the source = I ε Electric energy is: Electromotive force, , is the voltage generated by battery (how much energy per unit charge is available for the circuit including internal resistance) Resistors in Series connected in such a way that all components have the same current through them. • Resistors in Parallel Electric devices connected in parallel are connected to the same two points of an electric circuit, so all • components have the same potential difference across them. The current flowing into the point of splitting is equal to the sum of the currents flowing out at that point: • The greater resistance, the smaller current. A device that transforms mechanical energy into electrical energy is called a generator. A device that transforms electrical energy into mechanical energy is called an electric motor. A transformer is a device that transforms/change voltage. REVIEW PROBLEMS: 1. A circuit is wired with a power supply, a resistor and an ammeter (for measuring current). The ammeter reads a current of 24 mA (milliAmps). Determine the new current if the voltage of the power supply was ... a. increased by a factor of 3 and the resistance was held constant. b. held constant and the resistance was increased by a factor of 2. c. increased by a factor of 3 and the resistance was decreased by a factor of 2. d. decreased by a factor of 2 and the resistance was increased by a factor of 2. 2. A 541-Watt toaster is connected to a 120-V household outlet. What is the resistance (in ohms) of the toaster? 3. Consider two appliances that operate at the same voltage. Appliance A has a higher power rating then appliance B. a. How does the resistance on A compare with that of B. Is it (1) larger, (2) smaller, or (3) the same? 4. A computer system includes a color monitor with a power requirement of 200 W, whereas a countertop broiler/toaster oven is rated at 1500 W. What is the resistance of each if both are designed to run at 120 V? 5. Calculate the resistance of an aluminum (ρ = 2.8x10-8 wire that is 2.0 m long and of circular cross section Ωm) with a diameter of 1.5 mm.
Power of the source = ε I Electric energy is: Electromotive force, , is the voltage generated by battery (how much energy per unit charge is available for the circuit including internal resistance) Resistors in Series • connected in such a way that all components have the same current through them. Resistors in Parallel • Electric devices connected in parallel are connected to the same two points of an electric circuit, so all components have the same potential difference across them. • The current flowing into the point of splitting is equal to the sum of the currents flowing out at that point: The greater resistance, the smaller current. A device that transforms mechanical energy into electrical energy is called a generator. A device that transforms electrical energy into mechanical energy is called an electric motor. A transformer is a device that transforms/change voltage. REVIEW PROBLEMS: 1. A circuit is wired with a power supply, a resistor and an ammeter (for measuring current). The ammeter reads a current of 24 mA (milliAmps). Determine the new current if the voltage of the power supply was ... a. increased by a factor of 3 and the resistance was held constant. b. held constant and the resistance was increased by a factor of 2. c. increased by a factor of 3 and the resistance was decreased by a factor of 2. d. decreased by a factor of 2 and the resistance was increased by a factor of 2. 2. A 541-Watt toaster is connected to a 120-V household outlet. What is the resistance (in ohms) of the toaster? 3. Consider two appliances that operate at the same voltage. Appliance A has a higher power rating then appliance B. a. How does the resistance on A compare with that of B. Is it (1) larger, (2) smaller, or (3) the same? 4. A computer system includes a color monitor with a power requirement of 200 W, whereas a countertop broiler/toaster oven is rated at 1500 W. What is the resistance of each if both are designed to run at 120 V? 5. Calculate the resistance of an aluminum (ρ = 2.8x10-8 Ωm) wire that is 2.0 m long and of circular cross section with a diameter of 1.5 mm.