Evan's Space

Wonders of Physics


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Magnetic field around a magnet and an electromagnet

Electromagnet is like a ‘temporary magnet’. When a current flows through the solenoid, it will be magnetised. When the current is switched off, the eletromagnet loses its magnetism.

To make the electromagnet stronger,

1) Increase the number of turns in the solenoid.
2) Increase the size of the current.
3) Insert a soft iron core in the solenoid.
– iron is a soft magnetic material
– it can be magnetised easily
– it can be demagnetised easily


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N2007P1Q33 – Electromagnetism

A copper wire is taped to two wooden blocks which stand on a sensitive balance. When there is a current in the wire and a magnet is held in the position shown, the balance reading increases.

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Which other arrangement of magnet and current will give the same increased reading?

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Solutions: Option D

This question is rather direct. Applying FLHR, the force acting on the copper wire is downwards. Hence using FLHR again on the 4 options, only D creates the same downward force.

But what I wish to highlight in this question is for you to compare this with the other question which I posted earlier. They seems similar but they are different. View the other related question.