Basic Electricity - Senior Secondary 1 - Magnet and electromagnetism

TERM: 1^ST TERM

WEEK TEN

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: MAGNET AND ELECTROMAGNETISM

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Define a magnet

II.) Identify the types of magnet

III.) Explain the meaning of magnetic flux

IV.) Generate EMF using a magnet

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher explains the meaning of a magnet and discuss the types of a magnet	Students listens attentively to the teacher
STEP 2 EXPLANATION	Teacher describes the concept of magnetic flux and guide the students to use a magnet to generate EMF	Students exhibit attentiveness and active engagement
STEP 3 NOTE TAKING	The teacher writes a summarized note on the board	The students copy the note in their books

NOTE

MAGNET AND ELECTROMAGNETISM

A magnet is an object that produces a magnetic field, which attracts certain materials like iron, nickel, and cobalt. It has two poles: a north pole and a south pole. Opposite poles attract each other, while like poles repel.

Types of magnet

There are several types of magnets:

Permanent Magnets: These magnets retain their magnetism once magnetized and are commonly made from materials like iron, nickel, cobalt, and certain alloys. Examples include fridge magnets and magnets used in speakers.
Temporary Magnets: These magnets become magnetic only when exposed to a magnetic field. They lose their magnetism once the external field is removed. Examples include paperclip magnets and electromagnets.

Magnetic flux

Magnetic flux refers to the amount of magnetic field passing through a given area. It is represented by the symbol Φ (phi) and is measured in Weber (Wb). Magnetic flux depends on the strength of the magnetic field, the area it passes through, and the angle between the magnetic field and the area. Mathematically, magnetic flux (Φ) is defined as the product of the magnetic field strength (B) and the area (A) perpendicular to the magnetic field: Φ = B x A x cos(θ), where θ is the angle between the magnetic field and the normal to the area.

Draw magnet flux line

Generating EMF using a magnet

To utilize a magnet in generating electromotive force (EMF), you can employ the principles of electromagnetic induction. This phenomenon occurs when a magnetic field changes within a closed loop of wire, inducing a voltage (EMF) across the ends of the wire.

Coil of Wire: Start with a coil of wire, preferably made of a good conductor like copper. The wire should be wound around a core material, such as iron, to enhance the magnetic field's effect.
Move the Magnet: Move a magnet back and forth or rotate it near the coil of wire. As the magnet moves, it creates a changing magnetic field around the coil.
Induced EMF: The changing magnetic field induces an electromotive force (EMF) in the coil of wire, according to Faraday's law of electromagnetic induction. This induced EMF causes electrons to move within the wire, creating an electric current.
Utilize the Current: The induced current can be used to power electrical devices, charge batteries, or perform other useful tasks. It's essentially converting mechanical energy (the motion of the magnet) into electrical energy.

EVALUATION: 1. Define a magnet

Mention the two types of magnet
What is magnetic flux
Describe how you can generate EMF using a magnet

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively