(PP9) strength of a magnetic field

• the strength of the magnetic field depends on the current in the coil, the number of turns in the coil and the material used as the core of the coil
• Independent Variable is the current in the coil.
• Dependent Variable is the strength of the electromagnet, indicated by the number of paper clips that the electromagnet can hold. 
• Control Variables are the material of the core, the number of turns of the electromagnet coil, size of paper clips.
• Prediction - as the current increases, the electromagnet will get stronger and hold more paper clips.
• The magnetic field is caused by the current flowing in the wire.

  The bigger the current the stronger the magnetic field and hence the stronger the electromagnet.
• Ensure that the paper clips are the same size and material.
• As the current increases the number of paper clips held also increases.

  This means that the strength of the electromagnet increases with increasing current.
• We can say that, the strength of the electromagnet is directly proportional to the current.

  If you double the current, you double the strength of the electromagnet.
• A second experiment can be carried out to investigate how the strength of the electromagnet depends on the number of turns in the coil.
• As the number of turns increases the number of paper clips held increase.

  This means that the strength of the magnet increases with increasing number of turns in the coil.
• We can say that, the strength of the electromagnet is directly proportional to the number of turns in the coil.

  If you double the number of turns, you double the strength of the electromagnet.
• Repeat the experiment once more, keeping the current and number of coils the same.

  Replace the iron core with similar lengths of different materials such as steel, wood, plastic, aluminium and air.
• The strength of an electromagnet depends on:

  1. The size of the current.
  2. The number of turns in the coil.
  3. The material of the core.
• The strength of the magnetic field increases as:

  1. The current increases.
  2. The number of turns in the coil increases.
  3. An iron core makes a strong electromagnet which can be easily magnetised and demagnetised.