Physics 9702/52 — October/November 2016

A student uses a Hall probe to investigate the magnetic flux density due to a U-shaped electromagnet, as shown in Fig. 1.1.

Point P is equidistant from the poles of the electromagnet and distance $p$ is the vertical distance between P and the top of the electromagnet. The magnetic flux density is $B$ at point P.

It is suggested that the relationship between $B$ and $p$ is

where $N$ is the number of turns on the coil, $I$ is the current in the coil and $\alpha$ and $k$ are constants.

Design a laboratory experiment using a Hall probe to test the relationship between $B$ and $p$. Explain how your results could be used to determine values for $\alpha$ and $k$. You should draw a diagram, on page 3, showing the arrangement of your equipment. In your account you should pay particular attention to

• the procedure to be followed,
• the measurements to be taken,
• the control of variables,
• the analysis of the data,
• any safety precautions to be taken.