Copy of Rec08_Induction

Recitation08: PHYS 170: Electricity and Motion Manager:___Aryan Dixit_________________ Manages the group. Ensures that members are fulfilling their roles and the assigned tasks are being accomplished on time, and all members of the group are participating in the activities and understanding the concepts. Brainstormer:__________________ Always the first person to give a response to the question. This does not need to be an answer but instead could be a suggestion on how the group could go about formulating their response. Recorder:____________________ Records the names and roles of the group members at the beginning of each day. Records the important aspects of the group discussions, observations, insights, etc. Reflector:___________________ (Optional) Observes/comments on the group dynamics and behavior with respect to the learning process. The reflector must take notes (see end of document) about how well the group is operating (or what needs improvement) and why. Instructions: In your group of three or four (NOT five), randomly assign each member a role as listed above. As a group, complete the following. Submit one copy of your work per group at the end of the day to Blackboard under “Recitation Submissions”. Be sure to answer in complete sentences and to show all of your work. 1) David says that the size of the magnet determines whether a current can be induced in a coil of wire. You want to convince him that his idea is not correct. One way to do it is to design an experiment whose outcome might contradict a prediction based on David’s idea. a) Describe an experiment that would test David’s idea. Set up two experiments with coils of wire and magnets. In the first experiment, use a small but strong neodymium magnet and a coil of wire. In the second experiment, use a larger, but weaker, ferrite magnet with a similar coil of wire. Pass the magnets through the coils at the same speed and measure the induced current using an ammeter. b) What would David predict as the outcome of your experiment? David would likely predict that the larger magnet would induce a greater current in the coil, based on his belief that the size of the magnet is the key factor. c) How would the actual outcome of your experiment prove David’s idea to be incorrect? The actual outcome would likely show that the smaller neodymium magnet induces a stronger current than the larger ferrite magnet. This would demonstrate that the strength and type of the magnet, not just its size, are crucial in determining the induced current, thus disproving David's idea. 2) Fill in the table below with the words “higher”, “lower”, or “the same”. Step-Up Transformer (primary compared to secondary) Step-Up Transformer (secondary compared to primary) Step-Down Transformer (primary compared to secondary) Step-Down Transformer (secondary compared to primary) # of turns lower higher higher lower

Voltage lower higher higher lower Current higher lower lower higher Power The same The same The same The same

7) A transformer for a laptop computer converts a 120-V input into a 24-V output. a) Which has more turns of coil: the primary or the secondary? How can you tell without doing any math? The primary coil of the transformer has more turns than the secondary coil. This can be deduced without doing any math by understanding the basic principle of a transformer, which is that the ratio of the number of turns in the coils is directly proportional to the ratio of their voltages. Since the primary coil (input side) is at a higher voltage (120 V) compared to the secondary coil (output side) which is at a lower voltage (24 V), the primary must have more turns than the secondary. b) If the primary coil has 150 turns of wire, how many turns of wire does the secondary have? Show your work. Given that the primary coil has 150 turns and the transformer reduces the voltage from 120 V to 24 V, we apply the transformer equation relating the number of turns in the coils to their respective voltages: c) If the output current for the transformer is 1.8 A, what is the input current? The input current for the transformer, given an output current of 1.8 A, is approximately 0.36 A. This is calculated using the principle of conservation of power in an ideal transformer, where the input power (voltage times current on the primary side) equals the output power (voltage times current on the secondary side). 8) Suppose a simple loop of wire is immersed in a constant magnetic field. The magnetic field cannot be changed, and the loop cannot leave the magnetic field. Outside of attaching your simple loop of wire to a power supply (battery, generator, etc.), what could you do to the loop of wire to induce a current in it? Explain your reasoning. To induce a current in a simple loop of wire immersed in a constant magnetic field, without altering the magnetic field or removing the loop from the field, you can: 1. **Rotate the Loop:** By rotating the loop within the magnetic field, you change the angle between the magnetic field lines and the plane of the loop. This change in orientation affects the magnetic flux through the loop. According to Faraday's Law of Electromagnetic Induction, a change in magnetic flux through a loop induces an electromotive force (EMF), which in turn generates a current in the loop. 2. **Change the Area of the Loop:** If you can alter the shape of the loop to change its area, this will also change the magnetic flux through the loop. Increasing or decreasing the area of the loop changes the amount of magnetic field lines passing through it, which again, according to Faraday's Law, induces a current. Both methods involve altering the magnetic flux through the loop, which is the key to inducing a current according to Faraday's Law. The induced EMF (and hence the current) is proportional to the rate of change of the magnetic flux through the loop.

Reflector Notes: Observe and comment on the group dynamics and behavior with respect to the learning process. How well the group is operating or what needs improvement and why? Brainstormer Notes: How did your strategy change throughout your time in this role? How could you improve? Manager Notes: How did your strategy change throughout your time in this role? How could you improve?