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Physics Lab I
Electric Charges
Question | Answer |
---|---|
Study electromagnetic force by | examining the behavior of non-moving charges and charges in equilibrium. This is called Electrostatics. |
Charging by conduction (or direct contact) | A charged object is brought into contact with an uncharged one. Charge spreads across both objects, which are then separated. |
Polarization | A charged object near a neutral object separates + and - charges slightly in neutral object. Thus, the charged object and the oppositely charged near side of the neutral object will be attracted to each other. The neutral object remains neutral overall. |
Charging by induction | A wire connected to the ground can be used to drain off extra charge from one side of a polarized object, leaving it with a net charge. |
As you work through the lab, think about | where the charge is going and which of these effects are important |
Tool we are using | Electroscope with built-in or external deflection scale |
Section 5 | How to determine charge polarity |
UMVPS | low-current, high-voltage power supply |
Other equipment needed | insulated disk; insulated platform; round can; banana cables and alligator clips |
Electroscope purpose | Hold and measure charge |
A greater amount of charge will cause the vane to | deflect at a greater degree |
Charge will be created using a | power supply |
Three terminals | negative, mid-point, and positive |
Power supply pumps | charges (either positive or negative)from a large reservoir to a terminal |
We will connect one side of the power supply to the | electroscope case, which is in contact with the table |
Whichever terminal of the power supply is connected to the electoscope case will be | neutral, regardless of what the label on the power supply is. |
The terminal not connected to the electroscope will be the | high voltage (HV) lead. |
The HV lead can be either | positive or negative. |
How many terminals of the power supply is connected to ground in an experiment? | Only 1, but which particular terminal is grounded will vary from experiment to experiment |
An ideal measuring device will usually have | a well defined response curve |
If we double the amount of charge on the electroscope, we should expect to see | twice the deflection of the movable vane. This would be a linear response (plotting the deflection vs charge would be a straight line). |
Purpose of Experiment 4 | To determine if your device is lienar and what the minimum deflection you must see is before it becomes linear (and therefore reliable). |
Assume that the power supply is | linear |
A wire coming out of the positive lead is positive relative to | the electroscope case |