Lab 6: Current-induced Magnetic Fields Objective Here we want to study the behavior of a current-induced magnetic field when we vary the number of loops in the current carrying wire and the voltage supplied by the battery. Background It is known the magnetic fields can be generated by the motion of electrons in wires. Electric currents are thus considered to be a source of magnetic fields. In a solenoid (loops of conductive wire), it is possible to generate an electromagnet, which behaves similarly to a bar magnet. In the diagram below, the current I flows through the solenoid. The magnetic field produced along the central axis of the solenoid can be estimated using the following equation: N B = uoTi Where N is the number of turns in the wire, L is the length of the solenoid, and p b is the permeability of free space (1.26 x 10" N/A?). If the solenoid is connected to a battery (V), the resulting current (I) will generate a magnetic field and the solenoid will have a north pole and a south pole. Solenoid Methods For this lab we will use the electromagnetism simulation embedded in the Lab 6 Page that you found this manual in. You may also find this simulation on the Phet Interactive Simulation website built by University of Colorado Boulder. Please follow the instructions below and record anything you are asked to record in the blue boxes. Part 1: Initial Observations 1. When the simulation loads, you will see the same simulation that we used in Lab 5. Please select the Electromagnet tab at the top of the simulation. 2. Once the simulation loads, you will see a solenoid connected to a battery with current flowing through it and the resulting magnetic field. 3. Drag the compass around the electromagnet. Observe the red arrow (North Pole) of the compass needle. Is the left side of the solenoid the north or south end? How do you know? 4. Click on the Show Field Meter checkbox. Move the meter around the electromagnet. Does the field strength increase or decrease as you move the meter closer to the electromagnet? Part 2: Magnetic Field Strength with Varying Loops 1. Using the slider on the battery to set the Battery Voltageto 6 V. 2. Use the right menu to adjust the Number of Loops to 4 3. Now place the field meter about one inch (on your screen) to the left of the electromagnet so that the direction is as close to 0 as possible. 4. Record the total Magnetic Field strength (E) in table 1 below 5. Repeat three more times while decreasing the number of loops by one each iteration. Make sure to not move the meter throughout this process. 6. Using excel or google sheets, plot the number of loops on the x axis and the field strength on the y axis Table 1: Number of loops versus field strength Field strength |Gauss] Part 2: Questions 1. Does the plot you made of field strength as a function of loops look linear? If not, what does it look like? 2. Based on your data and graph, does the field strength increase or decrease as you increase the number of loops in an electromagnet? Is this what you would have expected? Explain Part 3: Magnetic Field Strength with Varying Voltage 1. Set the number of loops to 4 2. Use the slider on the battery to set the voltage to 10 V. 3. Record the strength of the magnetic field in in table 2 below. Do this in the same way that you did it in part 2 4. This time, repeat the measurement five more times, each time decreasing the voltage by 2 V until you reach 0. 5. Using excel or google sheets, plot the number of loops on the x axis and the field strength on the y axis Table 1: Voltage versus field strength Field strength [Gauss] Part 3: Questions 3. Does the plot you made of field strength as a function of loops look linear? If not, what does it look like? 0] 4. Based on your data and graph, does the field strength increase or decrease as you increase the number of loops in an electromagnet? Is this what you would have expected? Explain