# Electricity and Magnetism: Electromagnets Mr D. Patterson.

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Electricity and Magnetism: Electromagnets Mr D. Patterson

Outcomes explain that magnetic fields are associated with moving charges, and draw the field due to a current flowing through a long straight wire, a short coil and a solenoid. describe and apply the concept of force on a current carrying conductor in a magnetic field, and describe the factors which affect the force on a current-carrying conductor in a magnetic field—this will include applying the relationship: for perpendicular cases

A flow of positive charges will create a circular magnetic field. The direction of the field can be determined by the “right hand rule”. If negative charges are the cause of the current, use your left hand instead. An Electric Current Causes a Magnetic Field

Notation for 3D magnetic fields

E.g. Coil of wire An Electric Current Causes a Magnetic Field

E.g. Solenoid An Electric Current Causes a Magnetic Field

Force on a current carrying wire A current will produce a magnetic field. The produced magnetic field will interact with external magnetic fields which will apply a force to the current carrying wire

Force on a current carrying wire The right hand rule can will indicate the direction that the wire will be pushed.

Force on a current carrying wire The magnitude of the force on a current carrying wire: F is force (N) I is current (A) l is length of wire in the field (m) B is magnetic flux density (T)

Example A 5.00 m power line carries a 88.0 A current running from east to west. The Earth’s magnetic flux density in this area is 5.00 x 10 -5 T. What is the force felt by the power line?

Example A 5.00 m power line carries a 88.0 A current running from east to west. The Earth’s magnetic flux density in this area is 5.00 x 10 -5 T. What is the force felt by the power line? What about if the current runs west to east?

Example A 5.00 m power line carries a 88.0 A current running from east to west. The Earth’s magnetic flux density in this area is 5.00 x 10 -5 T. What is the force felt by the power line? What about if the current runs north to south?