Z. [2.5 pts] Draw a top-down 2D diagram of your setup in part E of the lab manual (imagine looking from above). This diagram should include: a. The cardinal directions (N,S,E,W) b. The direction of current in the wires (@ for into, and O for out of the page) c. The direction of the compass needle d. A vector representing the Earth's magnetic field e. A vector representing the wire's magnetic field at the compass f. The vector representing the total magnetic field at the compass g. Labels for measured distances (d), angles (0), and currents (1) E: MEASURING EARTH'S MAGNETIC FIELD The goal of this section of the lab is to measure the Earth's magnetic field. Since the B-field produced by the Earth is a vector, it has a magnitude and a direction. You have already measured the direction of the Earth's B-field, so all that is left to measure is its magnitude. By introducing another magnetic field (produced by the coil of wire attached to the wooden box) and using the compass, you will be able to measure the total magnetic field (Earth and wire fields combined), and use that information to infer the magnitude of the Earth's field alone. Practical considerations restrict the current to about 2.0 A. To overcome this we have multiple wires running parallel to each other, each carrying about 2.0 A. This setup also has a platform where you can place a sheet of paper and a compass. You can mark the angle of the compass needle on the paper. E1. Before you connect the loops of wire to the power supply, set the current limit of the supply to its maximum value, and set the voltage to 2.5 V. (This is just to make sure there is not too much current in the wires when you turn the supply on.) Then switch the supply to read current, and turn the power supply off. Cut a sheet of paper to fit around the wire and rest on the platform to record the direction of the magnetic field. Set up the circuit so that the "conventional" current is flowing upwards. E2, Test your setup: turn the power supply on and verify that you get a current of about 2.0 A. (This may not correspond to 2.5 V, which is ok) Do not leave the supply on for more than 10 seconds to avoid overheating, Note the current and the number of wires in your setup. of North E3. Using a compass observe and record the direction of the magnetic field at several points near the wire when the current is zero. Does this agree with the measurements you made in experiment C? 4. Place the compass somewhere on the box's platform. BEFORE you turn on the power supply, predict what you expect to see when the current is not zero. Use the fi ro. Use the figure on the right to help, and consider the right hand rule for generating magnetic fields from a straight current. Which way does the thumb point? Which way do the fingers point? ES, Now turn on the power supply, and which way the compass points with the current on. What does this have to do with the m o with the magnetic field where the compass is? Start with the compass north of the wires. Now move the compass to directly north of the wires. Which way does the field point there? Also note the field direction with the compass E, S, and W of the wires. E6. Is the direction and shape of the magnetic field you observe consistent with predictions made with the right hand rule? 7. Change the direction of the current through the straight wire. Is the magnetic field consistent with the right hand rule? . At what position relative to the wires is the magnetic field of the current perpendicular to the Earth's magnetic field (Choose N,SE,W)? Set the compass at this position. Are there any other places that you could place the compass so that the magnetic field produced by the current is perpendicular to Earth's field? Check with your TA to make sure you placed the compass at the right spot. West relative mpass E9, Record the angle the needle makes on the compass. Turn the power supply back on, letting the needle settle, and record the angle it makes with the current on. Does it point in the direction the right hand rule would suggest for it to? Why or why not? Adjust the current until you get to a 45 degree angle. 3.10 current to get 450 10. Calculate the magnitude and direction of the magnetic field as produced from the current alone at the compass' position. Remember to record the uncertainties for each measurement you needed to make for this calculation. Why is the uncertainty in the distance measurement larger than 1 mm? E11) The compass points in the direction of the local magnetic field, which can be the vector sum of magnetic fields produced by different es. Draw the vector diagram of the two magnetic fields and the resultant field. (Hint: you know the size and direction of the field from the wires, and the angles of the Earth's field and the resultant field.) What is the magnitude of the Earth's field as calculated from your measurements