The Motor Effect

Topics: Magnetic field, Electromagnetism, Magnetism Pages: 3 (958 words) Published: May 26, 2010
2.1 Motors use the effect of forces on current-carrying conductors in magnetic fields

2.1.1 The motor effect
The motor effect is where a force acts on a current-carrying conductor in a magnetic field. The right hand palm rule is used to find certain properties: fingers point to magnetic field, thumb points in DC direction and palm points to direction of the force. 2.1.2 Factors affecting the force acting on the current-carrying conductor

Forces are experienced by the electrons in the conductor and are affected by: * Length of conductor (longer conductor means more electrons hence more electrons experiencing the force) * Strength of magnetic field (more force on electrons)

* Amount of current in conductor (more current results in more electrons) * Angle between conductor and field
The amount of force can be calculated by F=BILsinѲ
2.1.3 Forces between parallel current-carrying wires
The force per unit length for two long parallel wires is proportional to the product of the currents and inversely proportional to their separation. Mathematically: F/L=Ki1i2/d where K is a constant of 2x10-7. The force is attractive if the currents travel in the same direction and repulsive if they travel in opposite directions. 2.1.4 Torque

Torque = Force X perpendicular distance from the fulcrum to the line of action of the force. Torque can be increased by increase force and/or increasing distance from the fulcrum to where the force is applied. 2.1.5 Torque on a current-carrying coil in a magnetic field

Torque on a current carrying conductor depends on:
* Number of coils (n)
* Strength of magnetic field (B)
* Size of current (i)
* Area of coil (A) and angle to field
By increase the number of coils, the torque increases since every coil experiences the same force. τ=nBiAcosѲ 2.1.6 Electric motors
Electric motors convert electrical energy into mechanical energy. A coil with current flowing in it, when placed in a magnetic field...
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