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

To indicate the magnetic field around the wire, draw concentric circles around the wire on the card. The direction of the magnetic field lines should follow the right-hand rule: if you point your thumb in the direction of the current, your fingers curl in the direction of the magnetic field lines.

To calculate the force on the roller, we can use the equation:

$F = B imes I imes L$

Where:

• B = 1.2 T (magnetic flux density)
• I = 2.5 A (current)
• L = 0.060 m (length of the roller)

Substituting the values into the equation:

$F = 1.2 imes 2.5 imes 0.060 = 0.18 ext{ N}$

Thus, the force on the roller is 0.18 N.

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

• 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 then points in the direction of the force experienced by the conductor.

You may illustrate this by drawing an appropriate diagram showing the orientation of your fingers.

An arrow should be drawn from the roller towards the contacts, indicating the direction of the force acting on the roller due to the magnetic field and current interaction.