Figure 6 shows the magnetic field of a magnet - Edexcel - GCSE Physics Combined Science - Question 3 - 2020 - Paper 1

To represent the magnetic field around the wire, draw concentric circles around the wire. The direction of the magnetic field lines can be indicated using arrows in a counter-clockwise direction when viewed from above, in accordance with the right-hand grip rule.

Using the formula:

$F = B × I × L$

we substitute the values:

$F = 1.2 ext{ T} × 2.5 ext{ A} × 0.060 ext{ m}$

Calculating this gives:

$F = 0.18 ext{ N}.$

Thus, the force on the roller is 0.18 N.

Fleming's left-hand rule states that if you hold your left hand with the thumb, first finger, and second finger mutually perpendicular to each other:

• The first finger represents the direction of the magnetic field (from north to south),
• The second finger represents the direction of current flow (from positive to negative),
• The thumb represents the direction of the force acting on the wire.
  Drawing a diagram depicting the arrangement can help clarify this concept.

An arrow should be drawn on Figure 8 pointing from the roller towards the direction of the current contacts to indicate the direction of the force acting on the roller.