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.