As it happens, today we did an experiment which can be explained in part by Fleming's Left Hand Rule. We clamped a wire to the table and tensioned it with masses hanging over the edge of the table. We wired it up so that alternating current was flowing through the wire. The wire passed between the poles of a strong magnet. Hence we had UVW from yesterday's post - cause, connection and effect. The current is the cause, the magnetic field the connection and the force (movement) is the effect. The current keeps changing direction but the magnetic field is fixed. Hence the force also alternates and the wire oscillates. If the frequency of oscillation is such that half a wavelength fits between the two wooden wedges, you get a "one loop" stationary wave - the fundamental mode. Changing the mass affects the tension in the wire and thus how easily it can vibrate. Hence the length of the stationary wave loop changes.
