For Fleming's left-hand rule, write down the three things that are 90° to each other, and next to each one write down the finger or thumb that represents it.

In Fleming's left-hand rule, the thumb, forefinger and central finger are three things that are 90° or perpendicular to each other.

(a) Thumb - represents force.

(b) Index finger- represents the magnetic field.

(c) Middle finger - represents current.

According to Fleming's left-hand rule, when left hand's thumb, forefinger (or, index finger) and centre finger (or, middle finger) are held mutually perpendicular to one another, the forefinger represents the direction of the magnetic field, the centre finger represents the direction of the current and the thumb represents the direction of the force.