2 131E 1 4 7. How much voltage is needed to produce a current of 6.0 A through a 24 V resistor? A. 4 V B. 18 V C. 30 V D. 144 V D because when you use the formula which is V-IR and you plug in the variables. V (6)(24) V = 144V and work is on paper. %3D 8. A short copper rod has a neutral charge. Negative charges are then applied to the right end of the rod. Which of the following describes the charge on the copper rod 5 s later? A. Both ends of the rod have a positive charge. B. The negative charge is spread evenly along the rod. C. Only the right end of the rod has a negative charge. D. All of the positive charge is in the middle of the rod. 9. A simple circuit is made using a battery, a light bulb, and some wire. Based on Ohm's law, which of the following should always decrease the brightness of the light bulb? A. using less wire in the circuit C. adding a second bulb in parallel B. adding a second bulb in series D. using a battery with a greater voltage Σ

2 131E 1 4 7. How much voltage is needed to produce a current of 6.0 A through a 24 V resistor? A. 4 V B. 18 V C. 30 V D. 144 V D because when you use the formula which is V-IR and you plug in the variables. V (6)(24) V = 144V and work is on paper. %3D 8. A short copper rod has a neutral charge. Negative charges are then applied to the right end of the rod. Which of the following describes the charge on the copper rod 5 s later? A. Both ends of the rod have a positive charge. B. The negative charge is spread evenly along the rod. C. Only the right end of the rod has a negative charge. D. All of the positive charge is in the middle of the rod. 9. A simple circuit is made using a battery, a light bulb, and some wire. Based on Ohm's law, which of the following should always decrease the brightness of the light bulb? A. using less wire in the circuit C. adding a second bulb in parallel B. adding a second bulb in series D. using a battery with a greater voltage Σ

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter17: Current And Resistance

Section: Chapter Questions

Problem 41P: Lightbulb A is marked 25.0 W 120. V, and lightbulb B is marked 100. W 120. V. These labels mean that...

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A typical cell phone consumes an average of about 1.00 W of electrical power and operates on 3.80 V. (a) What average current does the phone draw from its battery? (b) Calculate the energy stored in a fully charged battery if the phone requires charging after 5.00 hours of use.
When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
If electrical energy costs 0.12 per kilowatt-hour, how much does it cost to (a) burn a 100-W lightbulb for 24 h? (b) Operate an electric oven for 5.0 h if it carries a current of 20.0 A at 220 V?
The batteries of a submerged non-nuclear submarine supply 1000 A at full speed ahead. How long does it take to move Avogadro’s number (6.02 1023) of electrons at this rate?
If electrical energy costs 0.12 per kilowatt-hour, how much does it cost to (a) burn a 100-W lightbulb for 24 h? (b) Operate an electric oven for 5.0 h if it carries a current of 20.0 A at 220 V?
The- pair of capacitors in Figure P28.63 are fully charged by a 12.0-V battery. The battery is disconnected, and the switch is then closed. Alter 1.00 ms has elapsed, (a) how much charge remains 011 the 3.00-F capacitor? (b) How much charge remains on the 2.00-F capacitor? (c) What is the current in the resistor at this time?
(a) What is the resistance of a 1.00 102-O, a 2.50-k O, and a 4.00-kresistor connected in series? (b) In parallel?
An all-electric car (not a hybrid) is designed to run from a bank of 12.0-V batteries with total energy storage of age of 2.00 107J. If the electric motor draws 8.00 kW as the car moves at a steady speed of 20.0 m/s. (a) what is the current delivered to the motor? (b) How far can the car travel before it is out of juice"?
A potential difference of 1.00 V is maintained across a 10.0- resistor for a period of 20.0 s. What total charge passes by a point in one of the wires connected to the resistor in this time interval? (a) 200 C (b) 20.0 C (c) 2.00 C (d) 0.005 00 C (e) 0.050 0 C
Lightbulb A is marked 25.0 W 120. V, and lightbulb B is marked 100. W 120. V. These labels mean that each lightbulb has its respective power delivered to it when it is connected to a constant 120.-V source. (a) Find the resistance of each lightbulb. (b) During what time interval does 1.00 C pass into lightbulb A? (c) Is this charge different upon its exit versus its entry into the lightbulb? Explain. (d) In what time interval does 1.00 J pass into lightbulb A? (e) By what mechanisms does this energy enter and exit the lightbulb? Explain. (f) Find the cost of running lightbulb A continuously for 30.0 days, assuming the electric company sells its product at 0.110 per kWh.
Two conducting wires A and B of the same length and radius are connected across the same potential difference. Conductor A has twice the resistivity of conductor B. What is the ratio of the power delivered to A to the power delivered to B? (a) 2 (b) 2 (c) 1 (d) 12 (e)12