One of the two arms of the scale ends with a rectangular aluminium coil whose base measures 4 cm, immersed in the field of a powerful permanent magnet. The other arm has two sliding masses, which allow the item to obtain equilibrium at rest.
Allowing the current to flow through the use of the Variable L.T. Power Supply (code PH138216), or through the use of a battery in series with resistance, a force F appears between the magnetic field B and the electric current I, whose value is given by the Ampere law:
F = B • l • i • sin α
where l is the length of the conductor and α is the angle created between the conductor and the magnetic field. It is possible therefore to verify that the intensity of the force reaches its maximum when α=900° and it is zero when α=0°. Using the power supply, the value I of the electric current can be read directly on the built-in ammeter and, therefore, it is possible to deduce the permanent magnet’s induction value B. The experiment can be repeated replacing the permanent magnet with the solenoid, whose data sheets are included in this item. In this way it is possible to verify the ratio which gives the value of the magnetic field inside a solenoid. Scale sensibility: 10 mg.