Phys 221 - Lab 8_ Magnetic Force and Fields

Part 2a Questions: 1. Subtract the mass of the magnet assembly from the mass value in your data table. This is the net mass. Record these values as a column in your data table. Multiply the net mass by g = 9.8 m/s 2 . Why does this value equal the magnetic force FB? Power, I (A) Recorded Mass (g) Net Mass (kg) Magnetic force FB (kg m/s 2 =N) · 0 161.41 0 0 0.50 161.64 0.00023 0.002254 1.00 161.93 0.00052 0.005096 1.49 162.19 0.00078 0.007644 2.00 162.46 0.00105 0.01029 2.50 162.74 0.00133 0.013034 3.00 163.01 0.00160 0.01568 3.50 163.29 0.00188 0.018424 4.00 163.56 0.00215 0.02107 4.50 163.83 0.00242 0.023716 5.00 164.10 0.00259 0.025382 When we use the right-hand-rule, we can figure out that the magnetic force will point in the same direction as the normal force when the current is going right and the magnetic field is pointing towards the surface. The gravitational force also increased when the current was flowing because the normal force increased. So, the net mass multiplied by gravitational force is equal to the magnetic force created by the current carrying wire.

3. Segments 2-3 and 4-5 of the current loop (see Fig 3.) are also within the magnetic field of the assembly. Why are we justified in ignoring the force acting on these segments? Using the right hand rule and assuming the length of segments 2-3 and 4-5 are the same, the direction of the magnitude created by each current will be equal in magnitude but in opposite directions making them cancel each other out. So we can just ignore those forces. 4 Conclusion In conclusion, it is possible to conduct a lab to see the right-hand rule in action and to study the force exerted on a length of a current-carrying wire with changes in current and wire length. For Part 1 of the lab, the right hand rule was apparent in our results. For part 2a of the lab, I had a 10.3% error meaning our data correlated pretty well with the calculations done. For part 2b, I had a 77.87% error which is a really big jump from part A. I don’t entirely understand why such a big percent error occurred, but there could be many multiple sources of error. It could be the accuracy of the scale, the strength of the magnet, the current slowly decreasing as the lab kept going on, and the probe reading might not have been the most accurate. The R 2 was 0.991 for Part 2b so the length of the current and the measured net mass correlated well. The R 2 was 0.999 for Part 1 so the current and the magnetic force calculated correlated even better.