The Motor Effect

• A magnetic field is produced around a current-carrying wire.
• The strength of the magnetic field around a current-carrying wire is determined by the magnitude of the current flowing through the wire and the distance from the wire.
• A solenoid is a coil of wire which, when current passes through, creates a strong magnetic field.
• The magnetic field found inside a solenoid is strong and uniform.
• An electromagnet is a solenoid with an added iron core, which increases the strength of the magnetic field.
• The frequency of the a.c current is altered.
• This creates a different frequency of vibration in the cone.
• This produces a force which causes the cone to vibrate.
• A cone with a wire wrapped around it is connected to an a.c power supply and is placed in a permanent magnetic field.
• When current flows through the wire, it creates a second magnetic field, which interacts with the permanent field.
• The motor effect is when a force is exerted between a magnetic field and a current-carrying conductor placed in that field.
• The size of the force on a current-carrying wire in a magnetic field is affected by the magnitude of the current flowing through the conductor and the strength of the magnetic field that the conductor is placed in.
• The forefinger in Fleming’s Left-Hand Rule points in the direction of the magnetic field.
• The second finger in Fleming’s Left-Hand Rule points in the direction of current flow in the conductor.
• If the direction of current in a current-carrying wire placed in a uniform magnetic field is reversed, the direction of the force is reversed.
• Fleming’s Left-Hand Rule is used to determine the force experienced due to the motor effect.
• The unit used for magnetic flux density is Tesla, T.
• A loudspeaker works by using the motor effect to convert variations in the current of an electrical circuit into the pressure variations which produce audible sound.
• Loudspeakers make use of the motor effect to convert variations in the current of an electrical circuit into the pressure variations which produce audible sound.
• The strength of the force in a current-carrying wire placed in a uniform magnetic field is increased.
• The forces on the two sides perpendicular to the field experience forces in opposite directions, causing a rotational effect.
• The conductor must be at right-angles to the magnetic field it is placed in for the equation linking force, magnetic flux density, current and length to hold.
• An electric motor works by a coil of wire, carrying a current, being placed in a magnetic field.