Edexcel IGCSE Physics: Double Science 复习笔记:6.1.7 Fleming's Left-Hand Rule

Edexcel IGCSE Physics: Double Science 复习笔记:6.1.7 Fleming's Left-Hand Rule

Fleming's Left-Hand Rule

 

  • The direction of the force (aka the thrust) on a current carrying wire depends on the direction of the current and the direction of the magnetic field
  • All three will be perpendicular to each other
    • This means that sometimes the force could be into and out of the page (in 3D)

     

  • The direction of the force (or thrust) can be worked out by using Fleming's left-hand rule:

 

7.2.3-Flemings-Left-Hand-Rule

 

Fleming’s Left-Hand Rule can be used to determine directions of the force, magnetic field and current

 

 

Worked Example

Use Fleming’s left-hand rule to show that if the current-carrying wire is placed into the magnetic field between the poles of the magnet, as shown below, there will be a downwards force acting on the wire.7.2.3-WE-Flemings-LHR-Question-Image

 

Step 1: Determine the direction of the magnetic field

    • Start by pointing your First Finger in the direction of the (magnetic) Field.

     

 

Step 2: Determine the direction of the current

 

    • Now rotate your hand around the first finger so that the seCond finger points in the direction of the Current

     

 

Step 3: Determine the direction of the force

    • The THumb will now be pointing in the direction of the THrust (the force)
    • Therefore, this will be the direction in which the wire will move

     

 

7.2.3-WE-Flemings-LHR-Answer-Image 

Exam Tip

Remember that the magnetic field is always in the direction from North to South and current is always in the direction of a positive terminal to a negative terminal.Feel free to use Fleming's left hand rule in your exam, just don't make it too obvious or distracting for other students!

转载自savemyexams

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