This diagram shows a fixed horizontal wire passing centrally between the poles of a permanent magnet that is placed on a top-pan balance.

With no current flowing, the balance records a mass of 102.45 g. When a current of 4.0 A flows in the wire, the balance records a mass of 101.06 g.
a. Explain why the reading on the top-pan balance decreases when the current is switched on.
b. State and explain the direction of the current flow in the wire.
c. The length of the wire in the magnetic field is 5.0 cm. Calculate the average magnetic flux density between the poles of the magnet.
d. Sketch a graph, with balance reading on the vertical axis and current on the horizontal axis, to show how the balance reading changes when the current is altered.

Transcribed Image Text:

N pole wire S pole 102.45 g top-pan balance Figure 24.31