14/09/2018 Magnets and Compasses Objective: SWBAT identify materials with the property of magnetism. SWBAT draw the magnetic field of a magnet. SWBAT explain how magnetism makes a compass work. Essential Question: Which materials can be magnetized? How does this power work in the area surrounding the magnet?

Bellringer: True or False? All metals are magnetic. Two north poles repel. Two south poles attract. A plotting compass always points to the north pole of the Earth. The tape in a cassette player is magnetic. When a magnet is allowed to move freely, the end which points south is called the south seeking pole. Magnetism is a contact force. Fridge magnets are only attracted to fridges.

True or False? F T All metals are magnetic. Two north poles repel. Two south poles attract. A plotting compass always points to the north pole of the Earth. The tape in a cassette player is magnetic. When a magnet is allowed to move freely, the end which points south is called the south seeking pole. Magnetism is a contact force. Fridge magnets are only attracted to fridges.

14/09/2018 Hook: We Flippy, Mane We know where the north and south poles are, right? http://www.youtube.com/watch?v=IAGIrtz7L34 Just for fun: http://www.huffingtonpost.com/2013/04/20/magnetic-silly- putty-explained-video_n_3111911.html

Magnetic or non-magnetic? If a material is magnetic, it has the ability to apply forces on magnets or other magnetic materials nearby. OBJECT MAGNETIC

Which of these are magnetic materials? 14/09/2018 Which of these are magnetic materials? drinking glass copper pipe plastic ruler iron nails piece of paper aluminium drinks can gold ring piece of cobalt piece of nickel

How do two magnets interact? 14/09/2018 How do two magnets interact? Magnets have 2 poles: north and south. What do you think would happen if I brought different poles of magnets near this magnet? Just like charges, opposites attract and similars repel (or push away from each other).

So what happens when we break a magnet? 14/09/2018 So what happens when we break a magnet? This is because of Domain Theory.

Magnetic Fields The force from a magnet gets weaker as it gets farther away. Magnets are surrounded by invisible force fields that can reach out and apply non-contact forces on other magnetic objects. Its effect is strongest at the poles. Field lines always point north to south. The earth has a magnetic field that makes a compass needle point to the magnetic south.

Field Lines of Bar Magnet Magnetic field lines don’t start or stop. They travel from the north pole to the south pole.

Which diagram below best represents the magnetic field lines around a bar magnet?

The diagram below shows the lines of magnetic force between two north poles. At which point (A, B, C, or D) is the magnetic field strength greatest?

A student sprinkled iron filings around a bar magnet and observed their position as shown below. At which point (A, B, C, or D) is the magnetic field strongest?

Which diagram correctly shows a magnetic field configuration?