Tuesday, November 20, 2007

Electromagnetic Induction

FARADAY'S ELECTROMAGNETIC INDUCTION
Online Treasure Hunt
For High School Students Taking Physics (Science & Technology IV)
By: Ronor P. Escabarte
MOGCHS Faculty
Introduction
There are many application of electromagnetic induction. For example, the cassette tape is a magnetized tape. When played on a cassette player, the tape moves over a tiny coil and a small current is generated. The current is made bigger by the amplifier and is eventually fed to the loud speakers.

Electric guitars have “pick-ups” which are actually rows of magnets with coils around them. This magnetizes the strings and when the string vibrates current is induced in the coils.

Electric generators, transformers, rechargeable batteries. These are just some applications of electromagnetic induction.
To introduce the day’s lesson, recall Oersted’s remarkable discovery. In 1820, Hans ChristianOersted, a physics professor discovered in a classroom demonstration that an electric currentdeflects a compass needle. This shows that current produces magnetic field.
“Can the reverse of this phenomenon happen? Can magnetic field also
produce current?”
In today’s lesson we will find out who discovered electromagnetic induction, what it is, and why it is considered “a landmark in applied science”.

The lesson requires you to browse through some Web pages in which you will find out something about electromagnetic induction. A series of questions will guide your reading. Answers to the questions can be found in the Web pages, which are listed at random (and not according to the order of questions). Write your answer on the provided answer sheet and submit it after your schedule laboratory time.
You will work on by pair in answering the questions. Assign one member to take down notes and the other to write the answer in the provided answer sheet. Make sure you read between lines and be able to answer the questions accurately. Each question is 5 points each.
After successfully finding all the answers, move on to the Big Question.

Questions
1. Electromagnetic induction involves both electricity and magnetism. Which of the two is induced in the process and which one does the inducing? And what is another way of saying “to induce”?

2.In Faraday’s experiment, is it necessary to draw the magnet entirely into the coil? Why or why not?

3.Why is the principle of induction considered “a landmark in applied science”?
Consider the timeline of discoveries in electromagnetism (given in one of the websites below).
4.What is one insight you can form from looking at the timeline?

5. The invention of the dynamo was made possible by the discovery of electromagnetic
induction. What is the significance of the dynamo?

6.What invention by Faraday is the precursor of the modern transformer?

7.What is one of the medical applications of Faraday’s discovery of induced currents?

Resources

http://www.regentsprep.org/Regents/physics/phys03/dinduction/indapart.htm



The Big Question

Form a group consisting of five members and design a simple activity on electromagnetic induction using the following materials: coil of wire, bar magnet and current detector. Sumbit your output for the big question on December 3, 2007