On your first day at work as an electrical technician, you are asked to determine the resistance per meter of a long piece of wire. The company you work for is poorly equipped. You find a battery, a voltmeter, and an ammeter, but no meter for directly measuring resistance (an ohmmeter). You put the leads from the voltmeter across the terminals of the battery, and the meter reads 12.6 V. You cut off a 20.0-m length of wire and connect it to the battery, with an ammeter in series with it to measure the current in the wire. The ammeter reads 7.00 A. You then cut oil a 40.0-m length of wire and connect it to the battery, again with the ammeter in series to measure the current. The ammeter reads 4.20 A. Even though the equipment you have available to you is limited, your boss assures you of its high quality: The ammeter has very small resistance, and the voltmeter has very large resistance. What is the (resistance of 1 meter of wire?
On your first day at work as an electrical technician, you are asked to determine the resistance per meter of a long piece of wire. The company you work for is poorly equipped. You find a battery, a voltmeter, and an ammeter, but no meter for directly measuring resistance (an ohmmeter). You put the leads from the voltmeter across the terminals of the battery, and the meter reads 12.6 V. You cut off a 20.0-m length of wire and connect it to the battery, with an ammeter in series with it to measure the current in the wire. The ammeter reads 7.00 A. You then cut oil a 40.0-m length of wire and connect it to the battery, again with the ammeter in series to measure the current. The ammeter reads 4.20 A. Even though the equipment you have available to you is limited, your boss assures you of its high quality: The ammeter has very small resistance, and the voltmeter has very large resistance. What is the (resistance of 1 meter of wire?
On your first day at work as an electrical technician, you are asked to determine the resistance per meter of a long piece of wire. The company you work for is poorly equipped. You find a battery, a voltmeter, and an ammeter, but no meter for directly measuring resistance (an ohmmeter). You put the leads from the voltmeter across the terminals of the battery, and the meter reads 12.6 V. You cut off a 20.0-m length of wire and connect it to the battery, with an ammeter in series with it to measure the current in the wire. The ammeter reads 7.00 A. You then cut oil a 40.0-m length of wire and connect it to the battery, again with the ammeter in series to measure the current. The ammeter reads 4.20 A. Even though the equipment you have available to you is limited, your boss assures you of its high quality: The ammeter has very small resistance, and the voltmeter has very large resistance. What is the (resistance of 1 meter of wire?
A car battery with a 12 V emf and an internal resistance of 0.040 is being charged with a current of 50 A. What are (a) the potential difference V across the terminals, (b) the rate Pr of energy dissipation inside the battery, and (c) the rate Pemf of energy conversion to chemical form? When the battery is used to supply 50 A to the starter motor, what are (d) V and (e) Pr?
An automobile starter motor has an equivalent resistance of 0.075 Ω and is supplied by a 12.0 V battery that has a 0.015 Ω internal resistance.
Part (a) What current, I, in amperes, does the battery supply to the motor?
I = 133
Part (b) What is the terminal voltage, V, in volts, of the motor?
V = 10.00
Part (c) What power, P, in kilowatts, does the motor consume?
P =
1.6 for part c is incorrect.
1) A wire of initial length L0 and radius r0 has a measured resistance of 3 Ohms. The wire is drawn under tensile stress to a new uniform radius of r = 0.1r0. What is the new resistance of the wire? Assume the radius and the length of the wire can change.
30,000 Ohms
86,400 Ohms
16,666.67 Ohms
48,000 Ohms
2) A lightbulb marked “50 W [at] 120 V” is screwed into a socket at one end of a long extension cord in which each of the two conductors has a resistance of 0.6 Ohms. The other end of the extension cord is plugged into a 120-V outlet. Find the actual power of the bulb in the circuit described. Hint: You have three objects in a series circuit. Two of them are the conductors and the other object is the light bulb.
49.59 W
100 W
288 W
119.5 W
Chapter 25 Solutions
University Physics with Modern Physics (14th Edition)
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