The Effect of the Number of Coils on an Electromagnet On Its Strength

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The Effect of the Number of Coils on an Electromagnet On Its Strength

Aim: - To establish whether a variation in the number of coils will

affect an electromagnet's strength.

Scientific Knowledge: -

The concept of electromagnets is fairly simple.

An iron nail wrapped in a series of coils of insulated wire and then

connected to a battery, will enable the nail to pick up paper clips.

This is because the current emitted from the battery to the coils

magnetises the nail. This is known as an electromagnet. The current

passing through an electromagnet produces a magnetic field. Therefore,

the more turns of the coil you have, the greater the magnetic field

and the stronger the electromagnet. This will mean more paper clips

being picked up by the nail. The strength of an electromagnet can also

be altered by varying the current or voltage. The more induced

voltage, the stronger the electromagnet. An alternative way to

strengthen an electromagnet is to replace the core with a "soft" iron

core.

Prediction: -

An increase in the number of coils applied to the iron nail will cause

an increase in the number of paperclips being picked up. (a positive

correlation between the two variables)

This prediction derived from the scientific knowledge above -

'Therefore, the more turns of the coil you have, the greater the

magnetic field and the stronger the electromagnet.'

Apparatus: -

Iron nail (1)

Paperclips (several)

Power supply (1)

Coil (1)

Method: -

The method was relatively systematic. We first allocated various

people amongst our group to collect different equipment such as the

iron nail, paperclips, coil and power supply. Following that, we

connected everything securely and wrapped the coil five times around

the nail. We then switched on the power supply and set the voltage to

4V. We tested the number of paper clips the nail would pick up, each

time turning the power supply off and winding the coil five more times