1. Unit 4 Lesson 5 What Are Magnets? Copyright © Houghton Mifflin Harcourt Publishing Company

2. Unit 4 Lesson 5 What Are Magnets? Florida Benchmarks Copyright © Houghton Mifflin Harcourt Publishing Company SC.4.P.8.1 Measure and compare objects and materials based on their physical properties including: mass, shape, volume, color, hardness, texture, odor, taste, attraction to magnets. SC.4.P.8.4 Investigate and describe that magnets can attract magnetic materials and attract and repel other magnets.

3. Unit 4 Lesson 5 What Are Magnets? Magnets Are Everywhere Copyright © Houghton Mifflin Harcourt Publishing Company A magnet is an object that attracts iron and a few other materials. Magnetism is a physical property. Many magnets are made of iron. They attract objects that also are made of iron.

4. Unit 4 Lesson 5 What Are Magnets? Magnets Are Everywhere Copyright © Houghton Mifflin Harcourt Publishing Company Two factors that affect a magnet’s pull are barriers and distance. A thick barrier weakens a magnet’s pull on an object. The greater the distance between the magnet and object, the weaker the pull.

5. Unit 4 Lesson 5 What Are Magnets? Magnetic Fields and Poles Copyright © Houghton Mifflin Harcourt Publishing Company Each magnet has two ends, or poles. A magnetic pole is the part of the magnet where the force is the strongest.

6. Unit 4 Lesson 5 What Are Magnets? Magnetic Fields and Poles Copyright © Houghton Mifflin Harcourt Publishing Company One pole is “south-seeking,” and the other pole is “north-seeking.” The south-seeking pole is an S pole. The north- seeking pole is an N pole. Earth has an N pole and an S pole. As a result, the whole planet is a magnet.

7. Unit 4 Lesson 5 What Are Magnets? Magnetic Fields and Poles Copyright © Houghton Mifflin Harcourt Publishing Company Like poles are poles that are the same. Like poles repel, or push away, each other. Unlike poles are poles that are different. Unlike poles attract each other.

8. Unit 4 Lesson 5 What Are Magnets? Magnetic Fields and Poles Copyright © Houghton Mifflin Harcourt Publishing Company A magnetic field is the space around a magnet in which the force of the magnet acts. The magnetic field is strongest at the poles and weakest in the center of a magnet.

9. Unit 4 Lesson 5 What Are Magnets? Magnetic Force Copyright © Houghton Mifflin Harcourt Publishing Company A weak magnetic field forms around a wire when electricity flows through a wire. If a wire carrying electricity is wrapped around an iron object, such as a nail, an electromagnet forms.

10. Unit 4 Lesson 5 What Are Magnets? Magnetic Force Copyright © Houghton Mifflin Harcourt Publishing Company Wrapping more coils of wire around the nail strengthens the magnetic field. The magnet will be stronger. If the flow of electricity stops, the nail is no longer magnetic.

11. Unit 4 Lesson 5 What Are Magnets? Magnetic Force Copyright © Houghton Mifflin Harcourt Publishing Company Electromagnets are used in everyday objects. They are used in telephones, televisions, and motors. A motor is a device that uses electricity to make things move.

12. Unit 4 Lesson 5 What Are Magnets? Magnetic Planet Copyright © Houghton Mifflin Harcourt Publishing Company The whole planet Earth acts like a giant bar magnet. It has poles that attract and repel. It also has a magnetic field. A compass points toward the north pole.

13. Unit 4 Lesson 5 What Are Magnets? Magnetic Force Copyright © Houghton Mifflin Harcourt Publishing Company Earth’s magnetic poles and geographic poles aren’t in the same place. They are about 700 km apart. Iron in Earth’s core creates the magnetic field. The field looks much like that of a bar magnet.

14. Unit 4 Lesson 5 What Are Magnets? Magnetic Force Copyright © Houghton Mifflin Harcourt Publishing Company Magnets are used in computers, trains, MRIs, and junkyards.