A laboratory has five magnet assemblies. The uniform magnetic flux density in each gap is shown in the table.
| Magnet assembly | Magnetic flux density / T\text{T}T |
|---|---|
| A | 0.040 |
| B | 0.060 |
| C | 0.080 |
| D | 0.100 |
| E | 0.120 |
A stiff conductor is attached to one end of a light beam that pivots at its centre. A mass hanger is attached at the same distance from the pivot on the other side. A 0.050 m section of the conductor can be placed inside each magnetic field at right angles to the field.
When the beam is horizontal, the weight of the masses added to the hanger is equal to the magnetic force on the conductor. Use g=10 N/kgg = 10\ \text{N/kg}g=10 N/kg.
The laboratory also has a d.c. power supply, an ammeter, a variable resistor and a switch.
Devise an investigation to determine whether the magnetic force is directly proportional to magnetic flux density.
Your answer should include how the measurements would be used to reach a conclusion.