Capacitors and Capacitive Circuits Lab Introduction: A capacitor is an electrical circuit element that consists of two conductive plates separated by a dielectric material. It has the ability to store charge and to release the charge through a closed circuit, creating a current in the circuit There are five parts to this lab. Each part is a separate experiment to help you understand the physics and the mathematical models of a capacitor and of capacitive circuits. Note, however, that the direction of current flow shown in this simulation is opposite the convention that we use. Our convention is that positive charges move through the circuit from the positive terminal of the power supply (i.e.: the battery) to the negative terminal of the power supply. In this simulation, the current is shown to be carried by negative charges moving from the negative terminal of the power supply to the positive terminal of the power supply. In preparation for this lab, review the material covered on capacitors and capacitive circuits. Initial Setup: Open the PhET Capacitor simulation using the following link: https://phet.colorado.edu/sims/html/capacitor-lab-basics/latest/capacitor-lab-basics en.html When the link opens you will be offered two options: The Capacitance simulation and the Light Bulb simulation. Select the Capacitance simulation. Capacitor Lab: Basics Light Bulb Capacitance PHET: When the screen opens, several of the check boxes are unchecked and the Voltmeter will be parked in the grey box. Check all of the check boxes as shown below and leave the voltmeter parked. Capacitance 0.30 PF Plate Charges Top Plate Charge Bar Graphs Stored Energy Electric Field Current Direction O 6:0 mm Plate Area 15V - OThe voltage on the plates can be adjusted using the slider on the battery. The plate separation and area can be adjusted using the green arrows next to the top plate. You can get a more accurate measurement of voltage by placing the Voltmeter probes on wire leads coming from the batter to the capacitor. The battery can be connected and disconnected from the capacitor by moving the upper and lower switches onto and off of the battery leads. Spend some time playing with the simulation and familiarizing yourself with the controls. Part 1: Capacitance and Area C=EA/d: Objective: In this experiment you will study the relationship between capacitance and the area of a capacitor's plates. You will be setting the plate spacing to a fixed distance then adjusting the area of the plates and recording the value of the capacitance for each measurement of area. Procedure: 1. Reset the simulation and check all of the check boxes. 2. Disconnect the battery from the capacitor using the switch so that the circuit looks like the circuit in the introduction. 3. Set the distance, d, between the plates to 10.0 mm. 4. Select 7 evenly spaced area measurements from 100.0mm to 400.0mm2. 5. Create a table with the column headings shown and enter the area measurements that you have selected converting them to m2. d= 10.0 mm A (m2) C (F) 6. Using simulation adjust the area to each value in your table and record the capacitance C (in F). Analysis: 1. Enter your data in Excel and generate a least squares linear graph of capacitance vs area. 2. Record the equation of the of the line. 3. Using the mathematical model of a capacitor, calculate the permittivity of free space E.. 4. Calculate the percentage experimental error using the real value E.=8.85X10-12 C2/N.m Part II: Capacitance and distance C=E.A/d: Objective: In this experiment you will study the relationship between capacitance and the spacing between the plates. You will be setting the plate area to a fixed value then adjusting the spacing, d, of the plates and recording the value of the capacitance for each measurement of area. Procedure: 1. Reset the simulation and check all of the check boxes. 2. Disconnect the battery from the capacitor using the switch so that the circuit looks like the circuit in the introduction. 3. Set area, A, of the plate to 100.0 mm and 4. Select 7 evenly space distances between 2.00mm and 10.0 mm for the distance d between the plates.5. Create a table with the column headings shown and enter distance measurements that you have selected converting them to meters. A= 1.00x10-4 m2 d (m) 1/d ( m-1) C (F) 6. Calculate (1/d) for each distance measurement and enter the values in the table. 7. Using simulation adjust the distance for each value in your table and record the capacitance C (in F). Analysis: 1. Enter your data in Excel and generate a least squares linear graph of capacitance vs 1/d. 2. Record the equation of the of the line. 3. Using the mathematical model of a capacitor, calculate the permittivity of free space E.. 4. Calculate the percentage experimental error using the real value E.=8.85X10-12 C2/N.m2