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Name: ____________________________________________ Group: __________ Support activities – Second Year of Secondary Cycle Two ACTIVITY 23 ANSWER KEY Date: __________________ EST STUDENT BOOK: Chapter 5, pages 163–170 RELATED HANDOUT: Concept review 23 Magnetism and electromagnetism 1. Complete the following sentences, using the words or groups of words in the box below. You may use some words more than once. • • • • • • • • • • • • adding aligned artificial attract each other attraction circular cobalt coming out of conserve direction distance domains • • • • • • • • dynamic electromagnet(s) electromagnetism entering into ferromagnetic ferromagnetic core fingers geographic North Pole • increasing • like • magnetic field • magnetic field lines • magnetism • magnetized • mechanical • more powerful • motion • natural • nickel • not aligned • opposite • ore • • • • • • • • • • • permanent powerful right-hand rule rolled sharp blow solenoid south-seeking steel stopping temporary thumb Magnetism a) ________________________ describes all the phenomena caused by magnets. Magnets nickel are objects that can attract other objects containing iron, ________________________ or ore cobalt. Around 600 BCE, the Greeks discovered an ________________________ called © ERPI Reproduction and adaptation permitted solely for classroom use with Observatory. natural magnetite, which is a ________________________ magnet with this property. b) Certain metals have magnetic properties, which can be explained by their composition: they domains contain a set of regions called “________________________ ,” and each of these regions not aligned acts like a tiny magnet. The directions of these domains are ________________________ if magnetized the metal is not magnetized. If the metal is ________________________ , its domains will aligned be well ________________________ . The greater the number of aligned domains, the more powerful ________________________ the magnet. Observatory / Guide 11129-B 1 ANSWER KEY Support activities – Second Year of Secondary Cycle Two ACTIVITY 23 Magnetism and electromagnetism Name: ____________________________________________ Group: __________ Date: __________________ south-seeking c) Each magnet has a north-seeking and a ________________________ pole. By convention, the north pole of a magnet corresponds to the end that naturally turns toward the magnetic geographic North Pole pole that is located close to the Earth’s ________________________ . attraction d) Magnets interact with one another through forces of ________________________ and attract each other repulsion. In other words, opposite magnetic poles ________________________, and like ________________________ magnetic poles repel each other. These forces can act distance across a ________________________ . In a diagram of a magnetic field, they are magnetic field lines represented by ________________________. By convention, the lines are drawn coming out of entering into ________________________ the north pole and ________________________ the south pole of a magnet. cobalt e) EST Iron, nickel and ________________________ can be used to make artificial ________________________ magnets. To do so, they are exposed to the magnetic field ________________________ of another magnet. Substances with the ability to become ferromagnetic magnets are described as “________________________ .” They can be demagnetized if, sharp blow for example, they receive a ________________________ or are placed in a magnetic field of opposite polarity. f) EST Magnetic remanence is the ability of a material to acquire and conserve ________________________ magnetic properties. There are two types of magnets: temporary ________________________ magnets, which have low magnetic remanence and readily © ERPI Reproduction and adaptation permitted solely for classroom use with Observatory. acquire and lose their magnetic properties (for example, iron containing few impurities), and permanent ________________________ magnets, which have high magnetic remanence and are hard steel to magnetize and demagnetize (for example, ________________________ ). g) Electricity can be used to make magnets. The interaction between magnetism and electromagnetism electricity is called “________________________ .” An electric current can generate a opposite magnetic field, and the ________________________ is also true. Only dynamic ________________________ electricity can generate a magnetic field because the motion electrical charges must be in ________________________. right-hand rule h) Using the ________________________ , we can determine the direction of the magnetic thumb field lines of a live wire. The ________________________ points in the direction of the current, from the positive terminal toward the negative terminal. The fingers ________________________ wrapped around the wire show the direction of the magnetic circular field lines. These lines are ________________________ . Observatory / Guide 11129-B 2 ANSWER KEY Support activities – Second Year of Secondary Cycle Two ACTIVITY 23 Magnetism and electromagnetism Name: ____________________________________________ i) Group: __________ Date: __________________ EST To increase the intensity of the magnetic field of a live wire, it can be rolled ________________________ into a coil of regularly shaped loops to form a solenoid magnetic field ________________________ . This formation will have a ________________________ that resembles that of a bar magnet. However, three characteristics distinguish one from the solenoid other: The magnetic field of a ________________________ can be switched on or off stopping simply by ________________________ the current flow. It is possible to change the direction ________________________ of its magnetic field lines by reversing the current direction. Finally, the intensity of its magnetic field can be increased by increasing ________________________ the number of loops or by increasing current intensity. j) EST A solenoid can be transformed into an electromagnet ________________________ by adding a ferromagnetic core ________________________ inside the coil. The magnetic field is produced by both the ferromagnetic core solenoid and the ________________________ . The resulting magnet is very powerful Electromagnets ________________________ . ________________________ have the same advantages as adding solenoids, but their magnetism is increased by ________________________ the ferromagnetic core. They are widely used in the field of electricity, notably to transform mechanical electrical energy into ________________________ energy. 2. The figure below represents the Earth, which is a large magnet. Complete the figure with the following terms. – geographic North Pole – North Magnetic Pole – geographic South Pole © ERPI Reproduction and adaptation permitted solely for classroom use with Observatory. – South Magnetic Pole Geographic North Pole South Magnetic Pole North Magnetic Pole Geographic South Pole Observatory / Guide 11129-B 3 ANSWER KEY Support activities – Second Year of Secondary Cycle Two ACTIVITY 23 Magnetism and electromagnetism Name: ____________________________________________ Group: __________ Date: __________________ 3. The circles below represent compasses. In each situation, draw the needles of the compasses, using an arrow to show the direction they point. b) a) 4. Draw the magnetic field of each of the magnets below. b) a) 5. EST Draw the magnetic field lines for each of the solenoids below. © ERPI Reproduction and adaptation permitted solely for classroom use with Observatory. a) b) Observatory / Guide 11129-B 4 ANSWER KEY Support activities – Second Year of Secondary Cycle Two ACTIVITY 23 Magnetism and electromagnetism