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

To represent the magnetic field produced by the current in the wire, draw concentric circles around the wire on the card, indicating the direction of the field lines. The direction of the magnetic field can be determined using the right-hand grip rule, where the thumb points in the direction of the current and the fingers curl around in the direction of the magnetic field.

Using the formula for force, we have:

$F = B imes I imes L$

Substituting the given values:

$F = 1.2 \, T \times 2.5 \, A \times 0.060 \, m$

Calculating:

$F = 1.2 \times 2.5 \times 0.060 = 0.18 \, N$

Thus, the force on the roller is 0.18 N.

Fleming's left-hand rule states that if the thumb, first finger, and second finger of the left hand are held perpendicular to each other, the following can be determined:

• The first finger points in the direction of the magnetic field (from north to south).
• The second finger points in the direction of the current (from positive to negative).
• The thumb indicates the direction of the force acting on the roller.

A diagram can be drawn to illustrate this, showing the fingers at right angles and indicating their respective directions.

An arrow should be drawn from the roller towards the contacts, indicating the direction of force on the roller.