Wire Resistance & Ohm's Law

Name __________________________ Wire Resistance and Ohm’s Law

Go to http://phet.colorado.edu/simulations/sims.php?sim=Ohms_Law and click on Run Now.

Wire Resistance and Ohm’s Law

Procedure Part I Wire Resistance: open the PhET Simulation Electricity, Magnets, and Circuits ( Resistance in a Wire.
As wire length (cm) increases, the resistance (Ω) _increases________
As wire area (cm2) increases, the resistance (Ω) _decreases_________
As wire resistivity (Ωcm) increases, the resistance (Ω) _increases____
Procedure Part II: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law mA is milliamps, and _1,000_____ milliamps equals one Ampere. • Move the potential (volts) and resistance (ohms) sliders and observe the current (amps)
As voltage increases, current _increases__________.
As resistance increases, current _decreases (slows)__.
Fill out the tables below and check your work in the simulation. ( ½ pt each ) • Remember, the simulation shows milliamps. • You should show Amperes V = I * R
|8.0 V |.01 A |800 Ω |
|2.0 V |.044 A |450 Ω |
|0.2 V |.0058 A |430 Ω |
|6.9 V |.069 A |100 Ω |
|6.4 V |.0213 A |300 Ω |

Conclusion Questions: ( ½ pt each)
1. Incandescent light bulbs have a very thin filament that glows when hot. Thin filaments have very / low resistance.
2. The 12V battery in your car operates a 25 amp car stereo. What is the resistance of this stereo system? _0.48 Ω ___
3. A “2D” Maglite flashlight runs on 3.0V. What is the current through the bulb if resistance is 15 Ω ? _.20 amps____
4. How many volts must an iPod charger provide to charge an iPOD using .85 Amps at 35 Ω? _29.75 V__________
5. You need to buy a long extension cord to power a stereo