Magnetism

Magnetism

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Further Resources
This task is about magnetic fields.

Question

a)  A steel knitting needle is magnetised by stroking it 50 times in one direction with the north pole of a powerful bar magnet until it becomes magnetised.
     What happens when this knitting needle is cut in half?

    • It becomes two magnets, each has a north and south pole. 

    • It becomes two magnets, one has a south pole but no north pole; and the other has a north pole but no south pole. 

    • It becomes two magnets, one has a strong south pole and a weak north pole; and one has a strong north pole and a weak south pole. 

    • It loses its magnetism once it has been cut into two pieces.

Question Change answer

b) Draw on the diagram below:
  1. The lines of the magnetic field that would occur around and between the two magnets when they are pushed together.
  2. The direction the field flows in.
Task administration: 
This task can be completed with pencil and paper or online.
Level:
5
Curriculum info: 
Science, Knowledge, Physical World
Keywords: 
physics concepts, forces, force fields, magnetism, magnets
Description of task: 
Students answer a multiple choice question about what happens when a magnetised object is cut in half, and then draw the lines of the magnetic field around two magnets.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Interpret representations

Scientists represent their ideas in a variety of ways, including models, graphs, charts, diagrams and written texts. This resource provides opportunities to discuss the advantages and disadvantages of using diagrams to communicate science information.

Science capabilities: 
Interpret representations
Answers/responses: 
  

Y10 (10/1997)
a) (A) It becomes two magnets, each has a north and south pole.  difficult
b) Field shape accurate as below:

Direction of flow south to north.		 very difficult
 
 
 
 
 
very difficult
Diagnostic and formative information: 
 

Common error
a)
45% of students answered (D) It loses its magnetism once it has been cut into two pieces.
14% of students answered (C) It becomes two magnets, one has a strong south pole and a weak north pole; and one has a strong north pole and a weak south pole.