Question

8 (a) fig 8.1 shows a straight conductor ab connected to a cell. on fig. 8.1 show the direction of flow of current in the straight conductor ab. 1 (b) name a device that can be used to show the direction of the magnetic field around the straight conductor. (c) draw on fig. 8.1 the magnetic field pattern around the straight conductor ab. 2 (d) deduce what happens to the magnetic field if the polarity of the cell is reversed. 1

Explanation:

Step1: Determine current direction

In a circuit, current flows from the positive terminal of the cell to the negative terminal. So in conductor AB, current will flow from the end connected to the positive - terminal of the cell to the end connected to the negative - terminal.

Step2: Identify device for magnetic field direction

A compass can be used to show the direction of the magnetic field around a straight conductor. The needle of a compass aligns with the magnetic field lines.

Step3: Draw magnetic field pattern

The magnetic field lines around a straight current - carrying conductor are concentric circles with the conductor at the center. The direction of the field lines can be determined using the right - hand rule.

Step4: Analyze effect of reversed polarity

If the polarity of the cell is reversed, the direction of the current in the conductor is reversed. According to the right - hand rule, the direction of the magnetic field around the conductor is also reversed.

Answer:

(a) Current flows from the end of AB connected to the positive terminal of the cell to the end connected to the negative terminal.
(b) Compass.
(c) Draw concentric circles around the conductor AB. The direction of the circles can be determined using the right - hand rule.
(d) The direction of the magnetic field is reversed.