Q1. A student investigates the magnetic properties of three rods. Each rod is made of one of the following materials:


  • Soft iron
  • Steel
  • Wood

The student places each rod in a solenoid that is connected to a direct current power supply. The power supply is switched on for a short time. The student tests the magnetic strength of each rod by seeing how many paper clips it can pick up.

The number of paperclips picked up by each rod is shown in the table below.

Complete the table below to show which material (soft iron, steel or wood) each rod is made from and give the reason why. Part of the table has been done for you. Use information from the table.

[3 marks]

Q2. A student investigates the relationship between the magnetic flux density and the electromagnetic force on a current-carrying wire. The student has the equipment shown in the figure below:



When the current is switched ON, the magnetic field created in the red wire is pushed upwards by the fixed magnet pairs, which (due to the pivot) causes a downward force on the Force Meter. However, due to the slight readings, the student decides that the equipment is not sensitive enough.


(a) Give three ways the student should develop the investigation to improve the quality of results recorded. [3 marks]


  1. Use a higher current as the force depends on the current
  2. Use stronger magnets
  3. Use a force meter with a smaller range, eg 0.00 to 0.01

Make sure you give three clear and separate answers. You could also have said 'use a longer distance from pivot to increase the moment of the force on the wire' instead of any of the three answers given above. Remember that the force in the motor effect is increased by increasing the current and the field strength. You could also remember forces are increased by a greater distance from a pivot from your work on moments.

Q3. A student conducts an experiment to demonstrate how the strength of a magnetic field/induced electromagnetism increases with the number of coils of copper wire around an iron nail as shown in the diagram. The student uses this device to see how many paperclips can be picked up for the given number of turns shown in the table.




a) Use some graph paper to draw a graph of the result, with the number of turns on the x-axis. [3 marks]

b) Another student predicts that a 60 turn coil would hold 30 clips. Do you agree or disagree with this? Give a reason for your choice. [2 marks]

No, I do not agree with this prediction. If you look at the points plotted, there is a gradual curvature back towards the x-axis. If the points were plotted and joined as a best fit curve, it is clear that the number of points would come nowhere near thirty.

c) A second investigation was attempted to try and find the relationship between the current through the coil of an electromagnet and its strength. Outline briefly how this could be done listing any extra apparatus that is needed. [4 marks]

Two extra items would be needed, an ammeter and variable resistor. The number of turns of the coil, for example 30, should be fixed as a control variable for the whole investigation. The current would be increased in steps using the variable resistor and the number of paperclips attracted each time would be recorded. The number of paperclips attracted (dependent variable) would be plotted along the Y axis with the current used (independent variable) plotted along the X axis.


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