Faraday's Law
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Providence College *
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490
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Law
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Feb 20, 2024
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Uploaded by amandaheinz16
Amanda Heinz 04/17/22 PHY 122 L69 TA:Jae Sung Lee Faraday's Law Lab Report #8
Introduction: The purpose of this lab is to verify the direction of the current induced by a time varying magnetic flux. This direction is predicted by Faraday's Law Second objective is to quantitatively verify Faraday's Law for the case of a rotating loop in a magnetic field. The loop will be created by wrapping a long wire around the iOLab, the magnetic field will be provided by the earth, and the voltage will be measured by the High Gain Amplifier. Lenz' Law states that all magnetic field lines have no starting or ending point and due to this will curve back. This can be shown by using the equation B*dA=0. Faraday's Law states that the magnitude of the emf induced in a circuit is proportional to the rate of change of the magnetic flux that cuts across the circuit. It is predicted that if the predicted current equals the actual current then, Lenz’s Law will be true. Another prediction is that if the predicted voltage matches the experimental voltages, then Faraday’s Law is valid. Procedure: Part 1: Calibration & Magnet Orientation: 1.
Calibrate the magnetometer and find out the magnet orientation by moving a magnet towards and away from the coil on the iOLab device. Part 2: Experimental Setup: 1.
Plug one end of the wire minor G+ and screw in the long spin onto the iOLab force probe. 2.
Wrap the wire clockwise and pull it into the G- end. Part 3: Verifying Lenz’s Law: 1.
Face the iOLab along with the B field down. 2.
Hold a magnet high above the iOLab and push downwards. 3.
Repeat again but moving upwards and next to the device. 4.
Repeat both of these steps twice following: 5.
B and device facing upwards, then B facing upwards and device down, then B facing down and device up. Part 4: Taking Faraday’s Law Data: 1.
Hang the iOLab device off the edge of a table using the long spring. 2.
Spin it 3 times. 3.
Graph Ω
y on the parametric plot. 4.
4 data points on the positive and negative slopes. 5.
Calculate the theoretical values by using the parametric plot and find the diameter of the plot. 6.
Divide by 2 to find the value of B Results: Figure 1: Represents the data for Lenz’s Law Orientation 1
Orientation 2
Orientation 3
Orientation 4
Orientation 5
Orientation 6
Orientation 7
Orientation 8
Predicted Direction CW
CCW
CCW
CW
CCW
CW
CW
CCW
Actual Direction CW
CCW
CCW
CQ
CCW
CW
CW
CCW
Figure 2 (Left): Represents the first calibration. Figure 3 (Right): Represents the second calibration. Figure 4 (Left): Represents the data collected from step 3. Figure 4 (Right):
Represents the parametric plot of the rotating device Figure 5 (Left): Represents the graph from the parametric plot Figure 6 (Right): Represents the magnetometer Slope = -1.46 parametric plot
Figure 7 (Left): Represents the data used for the parametric plot for step 4 in Faraday’s Law Calculations: Theoretical EMF B=(-26.792uT—120.080)/2 = 46.644 uT Area: L*W= (.125m)(0.07m) = 0.00875m ^2 N= 8 coils = (46.644uT)(0.00875M^2)(8)= 3.26 Percent difference: E-A/E+A/2 *100= 3.26-1.46/3.26+1.46/2*100= 76.2712% Experimental EMF
Theoretical EMF
% Di
ff
erence 1.46 uT
3.26uT
76.27%
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Discussion/Conclusion: Overall, this lab wasn’t too successful. The Lenz’ Law was validated though the experiment in part 3. Using the right hand rule and Lenz’ Law to determine the direction of the current based on orientation of a magnet and the device. The theoretical and actual directions turned out to be equal which proves the law because the predicted current direct depended on the direction if the magnetic field and the device. In part 4, Faraday’s law tuned out to not be valid. The percent error was 76.27% which is extremely hight. A couple errors that must of thrown off the experiment was the placing and hanging of the iOLab was not correct and something interfered with it such as furniture, interference of data from another device as well as magnets. Another error could be that reading of the graph and picking out data points were not correct. Finally another error could be that calculations weren’t correctly done. Overall, the magnitude of the emf induced in a circuit was not proportional to the rate of change of the magnetic flux that cuts across the circuit. One possible way to carry out this lab in the future is to have a more controlled environment when performing this lab so there is less interference.