1. The total charge entering a terminal is given by q = 2e cos (6t), in uC. Determine the current at t= 0.25 s. 2. The resistance of a certain conductor , 300 mil diameter and 20 ft long is 200 x10^-3 0. Calculate its resistivity in micro-ohms-meter (uSN-m). 3. Determine the thermal coefficient of resistance of copper at 50°C, then use this value to determine the resistance of copper wire at 170°F if the resistance of this copper wire at 50°C is 50 N. The thermal coefficient of resistance of copper at 0°C is 0.004264/C°. 4. A battery has an EMF of 24.0 V and an internal resistance of 'r'. Its terminals are connected to a load resistance of 5.25 N. a. Find r and current in the circuit if the terminal voltage of the battery is 22.5V. b. Calculate the power delivered to the load resistor, the power delivered to the internal resistance, and the power delivered by the battery. 5. A 220V 600-watt electric coffee maker is used to make a total of 10 cups of coffee in 45 minutes. Determine the following : a. Current consumed by the coffee maker and the electrical energy consumed in kWh b. the rise in temperature of the device. Note: specific heat of water =4200 J/kg-K 1 cup = 236 grams

1. The total charge entering a terminal is given by q = 2e cos (6t), in uC. Determine the current at t= 0.25 s. 2. The resistance of a certain conductor , 300 mil diameter and 20 ft long is 200 x10^-3 0. Calculate its resistivity in micro-ohms-meter (uSN-m). 3. Determine the thermal coefficient of resistance of copper at 50°C, then use this value to determine the resistance of copper wire at 170°F if the resistance of this copper wire at 50°C is 50 N. The thermal coefficient of resistance of copper at 0°C is 0.004264/C°. 4. A battery has an EMF of 24.0 V and an internal resistance of 'r'. Its terminals are connected to a load resistance of 5.25 N. a. Find r and current in the circuit if the terminal voltage of the battery is 22.5V. b. Calculate the power delivered to the load resistor, the power delivered to the internal resistance, and the power delivered by the battery. 5. A 220V 600-watt electric coffee maker is used to make a total of 10 cups of coffee in 45 minutes. Determine the following : a. Current consumed by the coffee maker and the electrical energy consumed in kWh b. the rise in temperature of the device. Note: specific heat of water =4200 J/kg-K 1 cup = 236 grams

Physics for Scientists and Engineers, Technology Update (No access codes included)

9th Edition

ISBN:9781305116399

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter27: Current And Resistance

Section: Chapter Questions

Problem 27.5CQ: How does the resistance for copper and for silicon change with temperature? Why are the behaviors of...

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