Induced EMF in a Coil of Wire
Current travels from coil to conductor.Copyright Mainboard, Free Images, Getty Images http://www.sxc.hu/photo/862811
Students use a simple setup consisting of a coil of wire and a magnet to visualize induced EMF. First, they move a coil of wire near a magnet and observe the voltage that results. Then they experiment with moving the wire, magnet and a second, current-carrying coil. They connect the coil to a circuit and the current from the induced EMF charges a conductor.
To create MRI machines, engineers harness the power of radiation to produce images of the body while designing the equipment to protect patient and medical personnel from any dangerous side effects. To do this, engineers who develop MRI safety strategies must be aware of voltage changes occuring in metal objects within the magnetic field as result of the motion and strength of the field. At activity end, students consider this application with respect to MRI machines in the handout questions 1-3.
After this activity, students should be able to:
- Describe the motional EMF produced when a coil of wire moves through a magnetic field or a magnetic field moves through a coil of wire.
- Explain the induced EMF when a magnetic field through a coil of wire is increased.
- Charge a conductor using current from an induced EMF.
- Medical technologies include prevention and rehabilitation, vaccines and pharmaceuticals, medical and surgical procedures, genetic engineering, and the systems within which health is protected and maintained.
Grades 9-12
Do you agree with this alignment? - STEL-1O Assess how similarities and differences among scientific, mathematical, engineering, and technological knowledge and skills contributed to the design of a product or system.
Grades 9-12
Do you agree with this alignment?
- Results of scientific inquiry--new knowledge and methods--emerge from different types of investigations and public communication among scientists. In communicating and defending the results of scientific inquiry, arguments must be logical and demonstrate connections between natural phenomena, investigations, and the historical body of scientific knowledge. In addition, the methods and procedures that scientists used to obtain evidence must be clearly reported to enhance opportunities for further investigation.
Grades 9-12
Do you agree with this alignment?
- HS-PS3-5 Develop and use a model of two objects interacting through electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction.
Grades 9-12
This resource focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices- Develop and use a model based on evidence to illustrate the relationships between systems or between components of a system.Do you agree with this alignment?
Disciplinary Core Ideas- When two objects interacting through a field change relative position, the energy stored in the field is changed.Do you agree with this alignment?
Crosscutting Concepts- Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system.Do you agree with this alignment?
Do you agree with this alignment? - Develop and use a model based on evidence to illustrate the relationships between systems or between components of a system.
- 3231.5.8 Design an experiment to demonstrate the flow of charged particles and an electric current.
Grades 9-12
Do you agree with this alignment? - CLE 3231.5.2 Explore the flow of charge and electric currents.
Grades 9-12
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Each group needs:
- 2 gilley coils*
- rubber-coated NdFeB magnet
- multimeter
- 6V lantern battery or 5V DC power wupply
- 1000-ohm resistor
- 3 wires with alligator clip leads
- several hookup wires
- diode
- LED
- 100 μF capacitor
- breadboard
- Induced EMF in a Coil of Wire Handout (PDF), one per student
* Gilley coil induction sets are available online from a number of venders for ~$50. Improvise an easy alternative by winding a 2-inch diameter coil of 100 turns using 20 gauge magnet wire held together with duct tape.
We have learned that magnets can create a current in a wire. In this lab, we will experiment with this current and then use it to charge a capacitor. Learning more about the properties of magnetic fields will help us to better understand MRI machines so we can work to solve our MRI safety challenge.
- Gather materials and make copies of the Induced EMF in a Coil of Wire Handout (PDF).
- If desired, divide the class into small groups of two or three students each.
- Distribute the materials and handout.
- Direct students to follow the handout instructions to explore the current that is created when a loop of coil is passed over a permanent magnet.
- Then have them follow the instructions to create a circuit and use this induced EMF to light a diode.
- Conclude the activity by giving students time to individually prepare summary lab reports, as described on the handout and in the Assessment section.
Post-Lab Assessment
Lab Reports: As directed on the Induced EMF in a Coil of Wire Handout (PDF), have students individually prepare summary lab reports that include answering the four application questions, listing their observations, and describing any problems or issues that occurred during the lab. Review their lab reports to gauge their depth of comprehension. If desired, lead a class discussion in which students share their results, conclusions and answers to the questions, paying special attention to conclusions that relate to the ongoing engineering grand challenge of the unit.
- MRI Safety Grand Challenge for AP Physics
Contributors
Eric Appelt
Supporting Program
VU Bioengineering RET Program, School of Engineering, Vanderbilt University
Acknowledgements
The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.
Copyright
2013 by Regents of the University of Colorado; original © 2006 Vanderbilt University