You will get a shock any time that two parts of your body are at differentpotentials. Do not touch any of the exposed metal on the conducting wires whenthe power supply is on. It is safe to touch the rubberized outer coating ofthe wires, however. The rubber insulation is there to keep the wires fromconneting with other wires other than at their end junctions. It also keeps youfrom receiving shocks.
Ammeters MUST be connected in series. If the ammeter is connected inparallel with the resistor, a large current will pass through the meter'sinternal resistance - burning out the circuit. Make sure that your ammeter isconnected in series and that it is set to its highest setting, 20A. The powersupply we are using this week is only capable of producing 10A of current, sothe ammeter should never surpass this 20A limit.
Be sure to record the appropriate measurement errors for all of your data.
The lightbulbs in this experiment are rated to 5V. If connected to apotential difference greater than 5V, the bulb filament will melt and the bulbwill no longer be useful. No station will recieve more than one replacementbulb, so be careful to use low voltages on the power supply when taking measurements of the current and voltage for the lightbulb.
The component resistor is able to handle much higher voltages, but youshould use the same source voltages for the resistor as for the lightbulb inorder to have better basis for comparing the graphs of the two data sets.
Make sure all connections are tight. Jiggling of loose connections willaffect the electrical connection and can affect the current by 5%.
Take note of the orientation of the meter leads.
When you are finished taking data, make sure that the power supply andmeters are turned off.
Discuss your observations clearly and concisely, stating any conclusions youdraw from those observations. Make sure to support your conclusions byrefering to your data. For example, if you conclude that the voltage across abulb determines the brightness of the bulb, you should state the values of thedata you are comparing.
Be thorough in recording your observations during lab. This week you willbe submitting the lab manual sheets and the observation sections will begraded.
Plot both the graphs of section C on the same graph pape since the voltagevalues should be the same for both the lightbulb and the resistor. Make surethat you use two different colors or two different symbols (small circles,squares, triangles, etc.) to distinguish the two sets of data. Compare theshapes of the two lines and explain what the shape tells you about the behaviorof the lightbulb and the resistor.
| Section | Points |
|---|---|
| Purpose | 1 |
| Results | 3 |
| Graphs | 3 |
| Observations | 7 |
| Analysis | 6 |