To observe the magnetic field lines around current carrying solenoid.
- A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.
- The pattern of the magnetic field lines around a current-carrying solenoid is illustrated in Fig.1.
- The pattern of the field is similar to magnetic field around a bar magnet. One end of the solenoid behaves as a magnetic north pole, while the other behaves as the south pole.
- The field lines inside the solenoid are in the form of parallel straight lines. This indicates that the magnetic field is the same at all points inside the solenoid. That is, the field is uniform inside the solenoid.
Fig 1: Field lines of the magnetic field through and around a current carrying solenoid.
As performed in the real lab:
A cardboard, a circular coil, a battery, a key and iron filings.
- Take a cardboard with two holes in it.
- Pass a circular coil having large number of turns through these holes such that half the coil is above it and the remaining part is below the cardboard.
- Connect the free ends of the coil to a battery, and a plug key in series.
- Sprinkle iron filings on the cardboard and plug the key.
- Tap the cardboard few times and observe the pattern of iron filings that is formed on cardboard.
As performed in the Simulator:
- In 'Controls' section, vary the amplitude of the current and turn density of the coil by adjusting the respective sliders
- Observe the magnetic field intensity around the coil. You can rotate the coil to view the intensity.
- Click 'Reverse the current direction' check box to change the direction of current and observe the change in direction of magnetic field.
- Click on 'Observations' to get a better insight of the lab.
- You will observe that the field lines inside the solenoid are in the form of parallel straight lines.
- When the current is reduced to 0, magnetic field intensity around the solenoid reduces to 0.
- When we increase the amplitude of 'current' or the 'coil turn density', the magnetic field intensity around the solenoid increases.
- When we reverse the direction of current the polarity of the solenoid is also reversed.