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course Phy 202
4/13 10 amPhysics II 110411
1. Set up circuit 1 and measure the quantities you need to determine the rate at which potential energy changes across each bulb.
Report your results and how they were obtained from your data:
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Bulb 1==2.195 V* .0751 A=.0165 J/s
Bulv 2=.609 V * .0751 A=.046 J/s
To obtain, I simply multiplied the Volts by the current to get the potential energy
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2. Repeat with circuit 2.
Report your results and how they were obtained from your data:
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Bulb 1=2.63 V * -.158 A=-.42 J/s
Bulb 2= 2.49 V * -.158 A=-.39 J/s
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3. Set up circuit 3 and measure the quantities you need to determine the rate at which potential energy changes across the bulb and across the capacitor. Do these rates change with time?
As time changes the bulb in circuit 3 dims, and current and voltage change. Have the probe interface create graphs of the changing quantities, from which you can determine the changing rate at which potential energy changes across each circuit element.
From some of your graphs you can also determine how the resistance of the bulb changes with current. Do so.
Report your results and how they were obtained from your data:
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The initial voltage across the bulb and capacitor were 2.53 V and 2.84 V respectively and the current was 0.102 A.
Measuring the voltage across the bulb, starting with the initial, at 9 seconds, the voltage was 2.143 V and the current was .069 A. At 18 seconds, the voltage was 1.54 V and the current was .059 A. Solving for the rate of potential energy, at initial the rate of PE is .258 J/s. At 9 seconds, then 1.49 J/s. And 18 seconds rate of PE change=.0909 J/s.
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4. Circuit 4 is identical to circuit 3, except that you should use a resistor instead of a bulb. Repeat the preceding with this circuit. Does the resistance change with current?
Report your results and how they were obtained from your data:
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The voltage across the capacitor is .42 V.
Initial-- -2.631 V and .0264 A PE=-.069 J/s
30 seconds-- -1.894 V and .0194 A PE= -.0367 J/s
60 seconds-- -1.339 V and .0136 A PE= -.018 J/s
The resistance does change with the current.
@& The resistance is found by dividing the voltage by the current. It doesn't look like the resistance changed b a whole lot; looks pretty close to 10 ohms, except maybe on that last reading.
What about the bulb?*@
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5. Set up circuit 5, using a coil of magnet wire and a steel bolt for its core, and see if you can detect the (very short) time it takes the current through the coil to build.
Report your results and how they were obtained from your data:
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I measured this by using the graphing function and hit start then hooked up the final lead to the coil of wire. After the graph ran, I looked at the point where the current was initially hooked to the wire and the point where it seemed to be more constant. Based on my estimation it took approximately .2 seconds for the current to build.
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6. Set up circuit 6, using a piece of nichrome wire as the variable resistor. You can vary the resistance by sliding the contact point back and forth along the wire. Obtain a graph of current vs. time as you vary the resistance up and down.
Report your results and how they were obtained from your data:
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As with the last one, I used the graphing function. My results for current vs time.
Initial--.1431 A
5 seconds—.2070 A
10 seconds--.305 A
15 seconds--.499 A
17 seconds--.6217 A
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7. Set up circuit 7 and again vary the resistance of the nichrome wire up and down. Observe capacitor voltage vs. current. Are the two in phase?
Report your results and how they were obtained from your data:
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Time in seconds: Voltage (V) Current (A)
0 2.258 .0233
5 2.401 .0215
10 2.516 .0167
15 2.604 .0127
20 2.661 .0079
25 2.698 .0039
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8. Don't yet set up circuit 8. You won't be able to vary the resistance quickly enough to get an effect from the coil. However, based on your observations for circuit 5, how quickly do you think you would need to vary the current in order that the time required for the current to build in the coil might have a significant effect?
Report your results and how they were obtained from your data:
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Based on circuit 5, it would almost be infinitely fast. I’m not sure it would be completely possible to measure it given the circumstances.
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9. Set up circuit 9, using the double-pole-double-throw switch. Throw the switch at regular intervals, as quickly as possible while maintaining a regular rhythm. Slowly increase the resistance from minimum to maximum and observe the change in the relative phases of the current and capacitor voltage.
Report your results and how they were obtained from your data:
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Time in seconds: Voltage (V) Current (A)
0 .074 .0009
1.1 .035 -.0009
1.4 .068 .0018
1.9 .029 -.0006
2.1 .071 .0015
2.4 .035 -.0009
To obtain this data, one of us kept flipping the switch while the other started the graph. After it ran, we measured the peaks on the grpah to obtain data.
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10. Set up circuit 10 using two magnet wire coils and see if you can detect a brief current through the ammeter with each throw of the switch. If so, determine whether the current is in phase or out of phase, and to what extent, with the current through the first coil.
If you can detect a current, then see if you can detect a voltage.
Report your results and how they were obtained from your data:
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This was at the end of class and we were not able to detect the voltage.
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Self-critique (if necessary):
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Self-critique rating:
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&#Good responses. See my notes and let me know if you have questions. &#