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To make an electromagnet stronger The 3 C’s • More Coils • More Current • Use an iron Core Can you copy this please? Last lesson • Field around a wire • Electromagnetism Investigation Moving charges (currents) Moving charges (electric currents) also produce a magnetic field Conventional current – electrons flow in the opposite direction http://www.sciencebuddies.org Magnetic field around a straight wire You can use the right hand screw rule to decide which direction the field goes Stronger field closer to wire Magnetic field around a straight wire You can use the right hand screw rule to decide which direction the field goes Stronger field closer to wire Can you copy this? “Making electromagnets Investigation” To make an electromagnet stronger? To make an electromagnet stronger The 3 C’s • More Coils • More Current • Use an iron Core Today’s lesson • Field patterns around a wire, solenoid and coil. • The motor effect • Making a loudspeaker Field around a solenoid (coil) Field around a coil Can you gather around Mr Porter? The Motor Effect When a current is placed in a magnetic field it will experience a force (provided the current is not parallel to the field). This is called the motor effect. Can you copy this sentence into your books please. The Motor Effect The direction of the force on a current in a magnetic field is given by Flemming’s left hand rule. Thumb = Motion First finger = Field direction Centre finger = Conventional Current The Motor Effect Can you copy this please? WITH DIAGRAM! The direction of the force on a current in a magnetic field is given by Flemming’s left hand rule. Thumb = Motion First finger = Field direction Centre finger = Conventional Current Sample question In this example, which way will the wire be pushed? (red is north on the magnets) Sample question In this example, which way will the wire be pushed? (red is north on the magnets) Current Field Can you gather around Mr Porter? Again?! Building a loudspeaker These also use the motor effect Coil in here magnet Let’s read! Pages 210 and 213. The answer the questions on all pages. Finish for homework due 15th October
