together they exert a force on each other. Two like poles repel each other. Two unlike poles attract each other. Attraction and repulsion between two magnetic poles are examples of non-contact force. Describe what would happen if two North seeking Magnetic Poles were placed near each other, two South seeking Poles or one of each. Which part of a permanent magnet is the strongest? Investigate and draw the shape of the magnetic field pattern around a permanent magnet. Investigate the effect that two magnets have on each other in different orientations. 6.7.1.1 The differences between permanent and induced magnets. A permanent magnet produces its own magnetic An induced magnet is a material that becomes a magnet when it is placed in a magnetic field. Induced magnetism always causes a force of attraction. When removed from the magnetic field, an induced magnet loses most/all of its magnetism quickly. 0.5 Describe how an induced magnet is produced. Explain what is meant by a permanent magnet and give examples of materials that can become magnetised. What are the advantages of using an electromagnet rather than a permanent magnet? How can we make an electromagnet? Investigate how to make an induced magnet by stroking an iron nail with a permanent magnet. Investigate electromagnets and why they are referred to as temporary magnets. Find out why soft iron is used as the core in an electromagnet rather than steel. Investigate what affects the strength of a temporary magnet.
6.7.2 The motor effect Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 6.7.2.1 A wire carrying an electric current has its own magnetic When a current flows through a conducting wire a magnetic field is produced around the wire. The shape of the magnetic field can be seen as a series of concentric circles in a plane, perpendicular to the wire. The direction of these field lines depends on the direction of the current. The strength of the magnetic field depends on the current through the wire and the distance from the wire. 0.5 Describe how the magnetic effect of a current can be demonstrated. Use the ‘right hand thumb rule’ to draw the magnetic field pattern of a wire carrying an electric current. Demonstrate what happens when a foil strip with a current flowing through it is placed in a strong magnetic field. What happens if the direction of the current is reversed? Try to demonstrate the shape of the magnetic field by placing a wire through a piece of card with iron filings sprinkled near it. Apply a current through the wire.
6.7.2.1 A coil of wire carrying an electric current has its own magnetic field. Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire. The magnetic field inside a solenoid is strong and uniform. The magnetic field around a solenoid has a similar shape to that of a bar magnet. Adding an iron core increases the magnetic field strength of a solenoid. An electromagnet is a solenoid with an iron core. 0.5 Draw the magnetic field pattern for a straight wire carrying a current and for a solenoid. Describe the effect on the magnetic field of changing the direction of the electric current. Describe ways of increasing the magnetic field strength of a solenoid. Explain how an electromagnet can be made from a solenoid. Research uses of solenoids in medicine and in security doors. Plan an experiment to see if a coil of wire has a stronger magnetic field than a straight wire when both carry the same electric current. What are the control variables in this experiment? Find the magnetic pattern of a solenoid using iron filings or a plotting compass. How can the shape of the magnetic field inside the solenoid be determined?