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the motor effect power point .

Electromagnetism Basics

Wire Movement and Electromagnet Behavior

  • The direction of wire movement is influenced by current flow.

  • The end of the electromagnet that becomes a north pole is determined by the direction of the current.

  • Conventional Current: Flows from positive to negative.

Oersted’s Experiment

  • Demonstrates that an electric current creates a magnetic field around it.

  • Diagram:

    • A simple setup includes a wire with current flowing through it, causing iron filings placed around the wire to arrange themselves in a circular pattern, indicating the magnetic field direction.

Magnetic Field Direction

Maxwell’s Corkscrew Rule (Right-Hand Grip Rule)

  • Used to visualize the direction of magnetic fields produced by currents.

  • Diagram:

    • Right hand gripping a wire with fingers curling in the direction of the magnetic field lines while the thumb points in the direction of the current.

Magnetic Field Properties

  • Magnetic Field Lines:

    • Never cross each other.

    • Merge to create a resultant magnetic field.

Motor Effect

Definition

  • A current-carrying conductor in a magnetic field experiences a force, moving in a specific direction.

  • This interaction is known as the motor effect.

Fleming’s Left-Hand Rule (LHR)

  • Used to find the direction of force given the direction of current and magnetic field.

  • Considerations:

    • Direction of the force.

Predicting Force Direction Using Fleming’s LHR

  • Various potential movements of the conductor:

    • Up the page

    • Down the page

    • Out of the page

    • Into the page

Understanding Motor Effect

  • Factors influencing the motor effect:

    • Density of magnetic field lines (more density above a wire results in stronger resultant forces).

    • Magnetic Flux Density (B):

      • Formula: B = F/(Il)

      • Unit: Tesla (T), related to force experienced per unit current and length of conductor in a magnetic field.

Learning Check Example Calculation

  • A straight vertical wire carrying a downward current of 4.0 A in a 55 mT magnetic field.

    • Formula used: F = BIl

    • Result: Force magnitude is 0.022 N directed East.

Practical Investigation of Motor Effect

  • Exploring current's effect on force:

    • Adjust current using a rheostat and measure corresponding force.

  • Graph plotting:

    • Force vs. Current (F-N / I-A).

    • Linear relationship illustrated by F = BlI.

Coil and Magnetic Fields

  • Explanation of forces in a coil under magnetic field:

    • Situations when no forces are acting on sides of the coil.

  • Electrons in a wire:

    • Calculation of current and resultant electron flow amidst magnetic flux.

Understanding Electrical to Kinetic Energy Conversion

  • Discusses how electrical energy transforms into kinetic energy involving rotational motion.

Coil Behavior Under Currents

  • Questions to assess understanding of current direction, force application, and coil motion.

Magnetic Field Around Conductors

  • Right-Hand Grip Rule:

    • Thumb for current direction, fingers for field direction.

  • Mutual interaction of magnetic fields from parallel conductors:

    • Attraction or repulsion based on current flow direction.

Forces in Parallel Conductors

  • Force Calculation:

    • F/L = Force per unit length between currents I1 and I2.

    • μ0 (permeability of free space): 4π×10−7 T*m/A.

Ampere Definition

  • Defined as the current that generates a specific force when flowing between two parallel conductors in a vacuum.