WEEK 3 Magnetic Forces Quickly go through each picture and briefly describe how it relates to this unit.

What are magnets? Magnet: a piece of metal that attracts other pieces of metal Magnets are almost EVERYWHERE. They are made out of metal and iron. Define what a magnet is. Name examples in which one can find magnets. Engage the class by making them guess what each picture is.

Magnetic Poles Poles (cont.) Like poles repel, unlike poles attract North poles and south poles on magnets pull toward each other, called magnetic attraction. If the poles are the same, the two magnets will push each other away. They won't ever touch. This is called magnetic repulsion. Talk about how magnetic poles repel each other whereas unlike poles attract each other. Also, mention how each magnet contains a north and south pole.

North Pole vs. South Pole Pole North pole: the end of a magnet where lines of force flow out South Pole: the end of a magnet where lines of force flow in Name the key differences between the north pole and south pole.

Magnetic Field Magnetic field: space surrounding a magnet, in which force is exerted Produced by motion of electrical charges Field will continue to exist even if magnet is removed Explain thoroughly what a magnetic field is. Slowly explain, since this is completely new material. magnetic “field”

Magnetic Lines of Force A magnetic field is described by drawing the magnetic lines of force. The path traced by a North magnetic pole free to move under the influence of a magnetic field is called a magnetic line of force. The direction of a magnetic line of force at any point gives the direction of the magnetic force on a north pole placed at that point. Read off the slide, and also add that the magnetic lines of force are the lines drawn in a magnetic field along which a north magnetic pole would move. Explain that since the direction of magnetic line of force is the direction of force on a North Pole, the magnetic lines of force always begin on the N-pole of a magnet and end on the S-pole of the magnet. So, a line drawn from the South Pole of the compass to its North Pole indicates the direction of the magnetic field.

Properties of Magnetic Lines of Force The magnetic lines of force start from the North Pole of a magnet and end at its South Pole. The magnetic lines of force come closer near the poles of a magnet but they are widely separated at other places. The magnetic lines of force do not cross one another. When a magnetic compass is placed at different points on a magnetic line of force, it aligns itself along the tangent to the line of force Read off the important properties of the Magnetic Lines of force. Describe what a tangent is. Take a longer time to go through number 4.

Hard part’s over! Can you…? Can you…name the key difference between a north and south pole? Can you...name an example of an object is made out of metal? Can you…define what a magnetic attraction is? Can you...name a property of magnetic lines of force? True or false: Like poles attract, unlike poles repel Good work! Have the class answer these questions to see how much they paid attention.