Physics 137 Capacitance Activity Worksheet PDF

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Activity worksheet that goes with in class capacitance simulation....

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Capacitance Complete the following activity in groups. Each student is responsible for their own work but discussion is key! This activity will use the simulation found here: https://phet.colorado.edu/en/simulation/capacitor-lab-basics Click the ‘play’ button and choose “Capacitance” to get the appropriate simulation. Setup Begin with the battery set at 0 V. In the top right menu, ensure that “Plate Charges”, “Bar Graphs”, and “Current Direction” are checked. On the top menu ensure that “Capacitance”, “Top Plate Charge”, and “Stored Energy” are checked. Drag a voltmeter from the right-hand side onto the page, and put the leads on the grey circles outside the capacitor to measure the voltage difference across the capacitor. You are able to disconnect the capacitor from the battery with the switch at top or bottom, and you are able to adjust the plate separation and area of the capacitor by dragging the respective green arrows. Questions 1. Choose values for the separation and the plate area of the capacitor and note the resulting capacitance. a. Change the separation by a factor of 2, how does the capacitance chance? the capacitance decreases when the separation increases and inreases when the distance decreases

b. Return the separation to its original value then chance the area by a factor of 2, how does the capacitance change? the capacitance increases when the area increases and decreases when the area decreases

2. a. Given the behavior in the previous problem, how is the capacitance related to the separation and the plate area? (Hint: proportional or inversely proportional?) capacitance is inversly proportional to distance of plate separation and directly proportional to area.

b. What must the equation for the capacitance look like if we take 𝑑 as the distance and 𝐴 as the plate area? C=((epsilon*A)/d)

3. Make sure the capacitor is connected to the battery and then turn the battery up to some voltage. a. How does the charge move from the battery to the capacitor (and back)? The plate move closer and so capacitance decreases, the charges move toward the negative plate. When the plates move aparts and so the capacitance increases, the charges move to the positive plate.

b. How does the voltage of the capacitor read off of the voltmeter relate to the battery voltage? The voltage of the capacitor is the same as the battery because the battery controlls the voltage of the system. So whatever the battery voltage is, then the capacitors voltage is the same.

4. With the battery connected, change the capacitance of the capacitor by changing the distance and/or area. a. What quantity is held constant when the capacitor remains connected to the battery? The voltage remains the same when the capacitor remains connected to the battery.

b. How does the charge on the capacitor change when the capacitance is increased, with the battery connected? The charge on the capacitor remains the same when the capacitance is increased with the battery connected. This is because capacitance reflects the amount of charge able to pass through, not the amount that actually does.

5. With the capacitor charged by some amount, disconnect the battery, then change the capacitance by changing the distance and/or area. a. What quantity is held constant with the capacitor disconnected? The charge of the top plate remains the same when the capacitor is disconnected. This is because there is no where for the charges to move without the battery.

b. How does the voltage across the capacitor change when the capacitance is increased, with the battery disconnected? Voltage decreases when capacitance increases, and increases when capacitance decreases. Therefore, their relationship is inversely proportional.

6. Write down the equation that relates the voltage, charge, and capacitance of a capacitor. Given your answers to the previous two problems does this equation make sense? (Discuss proportionality of the quantities) Q=VC This makes sense because cvoltage and capacitance is directly proportional while charge and capacitance as well as charge and voltage are inversly proportional....