Magnetic Force on a Wire Lab Fwire S N Current in the wire goes into the page in this picture Fwire (pushing the magnet down, due to Newton's 3"d Law) Part A - Changing Current (1) Use the plate that has the longest horizontal wire (#38). Set up the apparatus, making sure that the wire is directly in between, parallel to, and not touching the magnet. (2) Record the mass (all digits) shown on the scale with the power supply OFF and record this in the table for 0 Amps of current. (3) Turn the CURRENT and VOLTAGE knobs all the way to the left. Turn ON the power supply. (4) Turn the VOLTAGE knob all the way to the right. (5) Adjust the current (about 0.5 Amps at a time), recording the corresponding mass (all digits) and the current in the table below. (6) Calculate the AM for each trial (see note below), and the magnetic force on the wire. Current Mass AM Force (A) (kg (kg) (N) Length of Wire = 42 cm 0 Amps 158. 3 Note: 3, 45 158.14 0 . 96 157. 96 AM is the change in mass from the original mass. This is the amount 1 . 51 157. 77- of mass we had to add to the 2. 51 157:61 original amount to cancel out the 2. 52 /15.7. 44 magnetic force. The weight of this added mass should equal the 2.97 157.28 magnetic force on the wire. 3. 52 /157 . 09 Part B - Changing Wire length (6) Repeat the process above using the four different length wires (#37, #38, #39, #40), and keeping the current fixed at the same value all the time. Try to get this current to be as close as to 2 Amps as possible. Turn the current off before removing the plate after each trial. Length Mass AM Force (m) (kg) (kg (N) 0 158. 30 Current in wire = 20 2 - 2 157. 95 4.2 157.61 3. 2 157- 90 2 158. 12 (7) Make a graph of Force vs. Current using the data in part A, including a trendline and its equation. (8) Make a graph of Force vs. Length using the data in part B, including a trendline and its equation. (9) Email your graphs to me in one spreadsheet. Include your group's names in the sheet itself.(1) Compare the magnetic force equation and the general equation for a straight line to explain why each of the two graphs you made will in fact be a straight line. Use this comparison to show what the value graphs be? of the slope of each graph should be in terms of I, L, and/or B. What should the y-intercept of your (2) What are the actual slope and y-intercept for the two graphs that you made? From each of your slopes, calculate the strength of the magnetic field using the appropriate expression from your answer to question 1. Calculate the percent difference between your two values. (3) Magnetic field strength is defined in terms of the force on (not from) a current-carrying wire. What is the source of the downward force on the magnet, then, causing its apparent weight to increase? (4) If a horizontal wire of length L and mass M is carrying a current I to the west and is floating stationary above the surface of the earth, what must be the magnitude and direction of the magnetic field in the region containing the wire? Explain how you are arriving at your