Electromagnetic Induction Savannah Sharp, Amelia Spilde, Brandon Mock, Lukas Binau

State and Explain Major Concepts Electromagnetic Induction is the inducing of voltage by altering the magnetic field in a conductor. The production of the voltage depends on the relative motion between the conductor and the magnetic field. It is explained in Faraday’s law : The induced voltage in a coil is proportional to the product of the number or loops and the rate at which the magnetic field changes within those loops.

Historical Perspective The concept was discovered in 1831 by Michael Faraday and Joseph Henry, independent scientists in seperate countries. This discovery helped make electricity commonplace, as the practice was previously voltaic cells.

Application of Concepts Electromagnetic Induction is used in many of today’s devices, including electric generators, magnetic flow meters, transformers and current clamps.

Think and Explain 1. The induced voltage in a coil is proportional to the product of the number of loops and the rate at which the magnetic field changes within those loops. 2. Work must be done to move a current-carrying conductor in a magnetic field. this is true whether the current is externally produced or produced as a result of the induction that accompanies the motion of the wire in the field. its also a matter of energy conservation. there has to be more energy input if there is more energy output. 3. Will move farther off because the same energy put in= the same energy put out. If some of the energy out is used for the light, less is available for bicycle motion 4. A transformer needs an alternating current that will create a changing magnetic field. A changing magnetic field also induces a changing voltage in a coil. 5. No, an efficient transformer cannot step up energy because that would violate the law of conservation of energy. 6. The 500-turn primary is 0.24 volts per turn. To get 12 volts (RMS) at the secondary, the number of turns required is 12 V / 0.24 V/turn = 50 turns. 7. 12V 8. to increase voltage between the secondary from the primary the turns for the secondary must be greater, a ratio of 2000:1 would boost 12-volts to 24000-volts 9. In general yes. If there are any magnetic components in your car (the frame is usually made of iron alloys) then as they approach the loop, the field intensity penetrating the loop will vary and create a current pulse. This pulse can be used to trigger traffic signals to give you a green light at an intersection. 10. The problem is that changing the voltage cannot change the amount of energy.   Even if conversion of mechanical energy to electrical energy and back again has 100% efficiency, all the energy from the generator is consumed in running the motor that runs the generator.

Review 1. They discovered that an electric current could be produced in a wire by simply moving a magnet in or out of a wire coil. 2. Voltage was induced by the relative motion between a wire and a magnetic field. 3. The greater number of loops of wire that move in a magnetic field, the greater the induced voltage and the greater the current in the wire. 4. It is more difficult to push the magnet into a coil with more loops because the magnetic field of each current loops resists the motion of the magnet. 5. Voltage and current are two different things. The amount of current produced by electromagnetic induction depends not only on the induced voltage, but on the resistance of the coil and the circuit that connects. 6. The frequency of the changing magnetic field is the same as the alternating voltage. 7. A motor converts electricity to work and a generator converts work to electricity. 8. Because of an external source of energy such as fuel, wind, or water. 9. A turbine causes the rotation. 10. A generator has the same ingredients as a motor- they work opposite, or in reverse of how a motor does. 11. Through a transformer. 12. It is intensified because of the magnetic domains of the iron. 13. A transformer changes the current. 14. It steps up the voltage. 15. If there are two loops there is twice the voltage. 16. 120 volts 17a. The alternating current is used to power the primary. 17b. The rate at which the magnetic field changes in the primary is equal to the frequency of the alternating current. 18. Because otherwise the process would result in extreme energy losses owing to the heating of wires. 19. An understanding of electromagnetic waves. 20. They are the same except Maxwell's law interchanges the roles of electric and magnetic fields. 21. In accordance to Maxwell's counterpart to Faraday's law, the changing electric field will induce a changing magnetic field. 22. Light is electromagnetic waves in a range of frequencies.

Background Information A charged particle in rod experiences a magnetic force that causes free charges in rod to move, creating excess charges at opposite ends. The excess charges generate an electric field and electric force opposite to magnetic force.      

Hypothesis Can we create an magnetic field with an electric current?

General Statement An electric current from the battery will cause the copper wire to move.

Apparatus and Materials Needed AAA battery copper wire neodyminium magnet

Step-By-Step Instruction 1. Coil the copper wire around the battery, with a hook set on the positive end knob and tight enough that the hook wont fall off. 2. Place the magnet on the negative end of the battery 3. Bend the wire to where it touches the magnet

Safety Precautions None

Analysis The current created a spiral magnetic field, turning the copper wire.

Conclusions Supported by Evidence The current from the battery moves the copper wire

Evaluation With a battery and a magnet, a magnetic field can be made.