Beatriz Fernandez Lab \"What the Flux.\" Michael Faraday discovered electromagnetic induction while working as curator of the Royal Academy of Science during the XIX Centaury. In this lab we are going to do the same. Materials: 0 Voltage Probe U Ruler - Lab Pro - Galvanometer - Computer with Logger Pro - Cables 0 Coil Set O AODC Power Supply - Transformer Coil Set - Magnetic Compass or AP 0 Cow Magnet Preliminary questions: 1. How would you calculate the Magnetic Flux? We will calculate the magnetic flux by using the formula Magnetic ux=B.A cos @ 'Where B=magnetic field A=area of surface @=angle between magnetic field and area of surface 1. Fill the table information Graph each graph and describe the relationships from the above graphs if they are linear explain the meaning of the slope and the y-intercepts. Table # 1: Number of Max. EMF (V) Average EMF (V) Positive Area (Vs) Negative Area (Vs) turns 200 400 800 1600 3200 Table # 2: Number of Turns Average Maximum EMF () Average Of Average EMF (V) 200 400 800 1600 3200 + Table # 3: Number of Turns Average Positive Area (Vs) Average Negative Area (Vs) | Average Total Are (Vs) 200 400 800 1600 3200Latest 3200 turns Time Potential (s) V) 0.000000 0.037 10 0.001300 -0.022 A W N 0.002600 -0.022 0.003900 -0.018 0.005200 -0.003 0.006500 -0.008 0.007800 -0.013 0.009100 -0.003 0.010400 -0.013 5 10 0.011700 0.007 1 1 0.013000 -0.018 12 0.014300 0.002 13 0.015600 -0.008 14 0.016900 -0.022 15 0.018200 -0.022 16 0.019500 -0.022 17 0.020800 0.002 18 0.022100 0.021 19 0.023400 -0.003 20 0.024700 -0.013 21 0.026000 -0.008 22 0.027300 0.036 23 0.028600 0.007 24 0.029900 0.007 25 0.031200 0.012 26 0.032500 0.012 -5 27 0.033800 0.007 28 0.035100 0.026 20 0.036400 0.002 Potential -10 0 5 10 151. The magnetic flux unit is the Weber, express the weber in terms of magnetic field and the area, and in terms of voltage and time. Flux=Magnetic field. Area or weber=Magnetic field. Area (Weber=Tm?) Also, e=N do/dt D=edt/N Or weber=voltage. Time (Weber=V sec) 2. On the space below, sketch a Flux vs. time graph for a magnet that falls through a coil? B. What is a galvanometer? How does it work? . A galvanometer is a device used to detect feeble electric currents in a circuit It consists of a coil suspended between the poles of a powerful magnet. As current passes through the coil, it deflects. It can be detected from the deflection on galvanometer needle. The deflection is proportional to the current passed through it. . Being a sensitive instrument, galvanometer cannot be used for the measurement of heavy current Procedure and Analysis: I. Detecting an Electromotive force, an induced emf on the outer coil. 1. Connect the DC power supply to the inner coil and the Galvanometer to the outer coil; 2. Turn on the power supply, check if you get deflection in the Galvanometer. 3. Turn off the power supply, check if you get deflections in the Galvanometer. 4. Press the middle bottom of the Galvanometer, and now turn the power supply on, then off, were there any deflections? Elaborate. 5. Turn on the DC power Supply and now insert the steel rod in and out of the inner coil, while pressing on the Galvanometer, what do you observe? Explain 6. Repeat steep five at different speeds, what do you observe? Explain NII. Measuring the Induced emf 1. Connect the voltage probe to the lab pro and the lab pro to the computer. Open Logger Pro. 2. Set data collection to 20 seconds duration and rate of 200 samples per second. 3. Repeat the Part I attaching the voltage probe to the outer coil. 4. Insert every corresponding graph and describe the graph correlating it to the event. III. Determining the average Magnetic Flux. CAUTION: Make sure that the cow magnet crosses the coil cleanly. Part A: EMF vs. Number of Loops 1. Assemble the apparatus shown by the professor. 2. Drop the cow magnet from 30 cm above the coil, measure the maximum, mean voltages for the positive part of the graph, and the positive and negative areas on the curve. 3. Repeat step 2 two more time. 4. Repeat steps 2 and 3 for other four coils (different number of turns;I 5. Create a table showing your results for the voltage and a table for the results of the area, calculate the total area under the curve. 6. Graph the relationship between the number of coils and the measured quanties. Part B: Part B ENIF vs. Velocity. '3'. Choose a 400 turns coil, set the apparatus that you used in Part A 8. Drop the cow magnet from 15 cm above the coil, measure the maximum, mean voltages, and the positive and negative areas on the curve. 9. Repeat step 8 two more time. 10. Repeat steps 8 and 9 for 30cm,45cm, 60cm, and 75 cm above the coil. 1 1. Create a table showing your results. 12. Graph the relationship between the number of coils and the measured quantities. Analysis: 1. Based on Part I and II, write a summary of the conditions needed to induce an emf in the outer coil? Describe any possible mathematical relationship. 0 The emf induced in a circuit is equal to the rate of change of magnetic ux through the circuit, Ad) written as: E: B__.. However, if the circuit contains N number of loops [solenoid] the same ux pass es through each loop, then the emf induced in each loop add AKD together which makes the total emf E=N B 2. What is the meaning of the area under the curve for the voltage vs. time graph? 0 The area under the curve represents the magnetic ux, the larger the area, the more magnetic ux through the coil. 3. What is the total area under the curve? Why do you think this happens? a The area is the ux through the coil, which is close to 0, indicating that there is almost equal amount of flux entering and exiting the solenoid. 4. Describe the relationships from the above graphs if they are linear explain the meaning of the slope and the y-intercepts. 5. What possible applications do the results of this experiment have? Please mention concrete examples. 0 In this experiment, we applied Faraday's Induction Law and thus used principles of electromagnetic induction which can be applied to a range of useful devices such as: transformers, which are devices that change ac electric power at one voltage level to another through the action of a magnetic eld, electric generators, and induction cooking devices. Conclusions: 0 Denitions: 0 Equations: Magnetic F lux, O Magnetic Flux: O Faraday's Induction Law, II Faraday's Induction E II Motional EMF. - Lenz's Law, 0 Physical Meaning of the slope and y-intercepts - Motional EMF - Textbook Correlation. 1. Definitions: a. Magnetic Flux. It's defined as the number of magnetic field lines passing through a given closed surface b. Faradav's Induction Law. It predicts howI a magnetic eld will interact with an electric circuit to produce an electromotive force {EMF}. c. Lenz's Law. It states that the current induced in a circuit due to a change in a magnetic field is directed to oppose the change in flux and to exert a mechanical force which opposes the motion. d. Motional EMF. It's an emf induced by motions relative to a magnetic field B. 2. Equations: a. Magnetic Flux. @W b. Farada v's Induction Law. gMwig c. Motional EMF. mm 3. Physical Meaning of the slope and yintercepts a. Average EMF vs #Turns I Slope. The correlation between the average EMF and number of Turns is almost 1(03987 exactly} which means both have a positive directly proportional relationship. I Yintercept. There is no official value when the number of turns ago, but theoretically the value is negative very close to 0. b. Average Positive Area vs #Turns I Slope. The correlation between the average EMF and number of Turns is almost 1 (0.9999 gm which means both have a positive directly proportional relationship. ii. I Yintercept. The theoretical value for when the number of turns $0 is 0.0006108 {almost 0}. c. Max EMF vs #Turns I Slope. The correlation between the average EMF and number of Turns is almost 1 which means both have a negative directly proportional relationship in direction down. I Yintercept. The theoretical value for when the number of turns $0 is 00006538 (almost 0}