# 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:

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.

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

#### 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!