My PBL Project

INTRODUCTION:

The project is making a hand cranked generator. The end of the crank that is inside the body of the device is covered in magnets. Around that is a little dead air space and then a crap ton of coiled wires. When you turn the crank, it spins the magnets creating a magnetic field. The magnetic field induces a current of electricity in the coiled wires. If it's a hand crank flashlight, the electricity is then stored in a bunch of capacitors and/or batteries.

MATERIALS:

- Hand cranked generator

-Electromagnetic Flashlight

-Magnetic compass

-Copper wire

-Miniature light bulb and base

-Tape

PROCEDURE:

First I find a way to see how i can change the brightness of the light and see the concept behind that. After that i record my data of my observations of cranking the generator. After that i test different the things to see if it affects the project such as bending the copper wire into a coil. Then i try reversing the direction I crank the generator and record my data. After that i draw a diagram of the field lines for the magnetic field with a wire coil vs the one without the wire coil. Lastly with the results i have obtained i calculate the magnetic flux along with the loop change.

SCIENTIFIC PRINCIPLE:

GENERATOR

The mechanical energy used to turn the loop is converted to electrical energy. A device that does this conversion is called a electric generator. Basically generator uses the turbine's rotary motion to turn a wire loop in a magnetic field. As the loop rotates, the effective area of the loop changes with time, including an emf and a current in an external circuit connected to the ends of the loop. When the are of the loop is perpendicular to the magnetic field lines, every segment of wire in the loop is moving parallel to he magnetic field lines. Therefore the magnetic field doesnt exert force on the changes in an part of the wire, so the induced emf in each segment is therefore zero.

FARADAY'S LAW

One main principle that follows my experiment is Faraday's law. Faraday's law serves as a summary of the ways a voltage may be generated by a changing magnetic environment. Faraday's law is a fundamental relationship which comes from Maxwell's equation. The induced emf in a coil is equal to the negative of the rate of change of magnetic flux times the number of turns in the coil. It involves the interaction of charge with magnetic field.

LEN'Z LAW

Another Principle that goes along with Faraday's Law is Lenz's Law. When an emf is generated by a change in magnetic flux according to Faraday's law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant.

MAGNET AND COIL

When a magnet is moved into a coil of wire, changing the magnet and magnetic flux through the coil, a voltage will be generated in the coil according to Faraday's Law. In the example shown below, when the magnet is moved into the coil the galvanometer deflects to the left in response to the increasing field. When the magnet is pulled back out, the galvanometer deflects to the right in response to the decreasing field. The polarity of the induced emf is such that it produces a current whose magnetic field opposes the change that produces it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. This inherent behavior of generated magnetic fields is summarized in Lenz's Law.

Driving question: How do Generators work?

A generator is a device that moves a magnet near a wire to create a steady flow of electrons. As the crank turns on a generator, the mechanical energy is converted into electrical energy.