In the following two videos, you can see how we make measurements in a circuit. We use a voltmeter to measure the potential difference between two points and we use an ammeter to measure the current at any point in the circuit.
Using the measurements I made in these videos, I want you to determine the resistance of the resistor.
Check your answer: E. 10 Ω
Putting it all together: current, resistance, and Ohm’s law
Pause & Predict 5.2.1
What diameter will result in the same resistance?
Pause & Predict 5.2.2
What is the current through the resistor?
Practice!
Practice 5.2.1
A 580-mm long tungsten wire, with a 0.046-mm-diameter circular cross section, is wrapped around in the shape of a coil and used as a filament in an incandescent light bulb. When the light bulb is connected to a battery, a current of 0.526 A is measured through the filament. What is the resistance in this tungsten filament? (Tungsten has a resistivity of 4.9 x 10-8 Ω·m)
Check your answer: D. 17.1 Ω
Practice 5.2.2
Light bulb A contains a coil filament made from a tungsten wire that is 580 mm long and has a 0.046-mm-diameter circular cross section. Light bulb B also has a coil filament made of tungsten, but it’s length is twice as long as the filament in light bulb A and it’s diameter is half that of light bulb A. What is the ratio of the resistance of light bulb B to the resistance of light bulb A?
Check your answer: D. 8.0
Practice 5.2.3
A 580-mm long tungsten wire, with a 0.046-mm-diameter circular cross section, is wrapped around in the shape of a coil and used as a filament in an incandescent light bulb. When the light bulb is connected to a battery, a current of 0.526 A is measured through the filament. What is the voltage of the battery that would produce this current in the filament? (Tungsten has a resistivity of 4.9 x 10-8 Ω·m)
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