U10370 [1002660]

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U10370 [1002660] | Manualzz

3B SCIENTIFIC® PHYSICS 1002660 Permanent Magnet Instruction sheet

12/15 MH

1 Neodymium magnets, each 20 mm in diameter and 10 mm in length 2 Threaded bolt made of black finished iron 3 Hand wheel made of stainless steel 4 Base apparatus made of black finished iron 5 Pole pieces made of black finished iron

  

Fig.1: Scope of delivery

1. Safety instructions

Magnets demonstrate considerable forces of attraction and repulsion, through which they harbor injury hazards through squashing or sharp metal slivers attaching to the magnet. For that reason magnets may not be removed from the threaded bolts or subjected to mechanical modifica tion. Certain magetic materials are toxic and/or slightly soluble and thus not completely sa fe. Performance degradation, material da mage and decay can result from, for exa mple, corrosion (keep in dry storage), chemical effects, opposing magnetic fields, high temperatures etc. Allergic reactions may be triggered by direct contact with magnetic material (e.g. against zinc and nickel).

Permanent magnets may not be exposed to radioactive radiation.

   

When permanent magnets are in motion or when current-carrying materials are moved through the magnetic field this can lead to the formation of eddy currents and thus to considerable heat build up in the material – risk of burns. Bear in mind that magnetic fields can dele te data stored on data media and can ad versely affect or destroy electronic as well as mechanical components, e.g. cardiac pacemakers. It is imperative that required safety distances be strictly adhered to. A dangerous cargo certificate is needed for air freight transportation. In spite of all these instructions the author is unaware of any negative influences for humans stemming from the magnetic fields of permanent magnets. 1

   

2. Description, technical data

The magnet with variable pole distance can be used together with the electromag netic experiment apparatus 1002661 for experiments on diamagnetism and para magnetism to determine the force being exerted on current carrying conductors as well as in the demonstration of eddy cur rents. Together with the Lorentz motor 1002662 a motor can be assembled without needing an iron core in the motor winding and which rotates only on the basis of the Lor entz force. Here the rotation direction – un like standard DC motors with twopole ar matures – is dependent on the current di rection. To fasten down the magnets within expe riment setups there is a bore hole with 8 mm diameter in the lower carrier plate and an M5 threaded hole arranged per pendicular to this. As such it is possible to either attach the magnets on a stand rod with 8 mm diameter or lock it in place with an M5 knurled screw or to screw it directly onto, e.g. the electromagnetic experiment apparatus using a knurled screw M8. The air gap between the Neodymium mag nets is adjustable from 2 mm up to 80 mm. The field intensity B which settles in along the imaginary center axis between the two magnets can be calculated as a function of the air gap width x as follows

1

:

Br

 

D

2

2

L

 

(2

L x

x

)

2 

x D

2 

x

2   

Here L stands for the total length of the magnets (2 x 10 mm = 20 mm) and D for the diameter (20 mm). Basically the mag netic remanence B

r

can only be deter mined via measurement because the man facturing tolerances can be significant. The value for the magnets used here should be around 1000 - 1300 mT. Assuming that the remanence amounts to B

r

= 1230 mT, then according to the Equation above for an air gap width of x = 5 mm we obtain a field in tensity of B = 826 mT.

3. Operation principle

The magnet can be used in 4 positions: – standing upright, as in Fig. 1 – lying on on side – standing on ist head – standing on ots longer side (for experi ments in the vertical magnetic field)

 

By using the pole pieces included with the delivery the dimension of the magnetic field can be increased. When attaching or re moving the pole pieces proceed very carefully to avoid crimping or squashing your fingers. The measurement of the air gap width should be carried out using a plastic ruler or a vernier caliper made of plastic, in or der to avoid any undesired magnetisation of the measuring instrument. If the air gap width was determined for a certain position of the hand wheels, then the air gap width can continue to be determined on the basis of the number of turns made on the hand wheels for the rest of experiments since one full turn corresponds to a distance of 2.5 mm.

4. Maintenance and storage

If necessary, the iron components can be wiped clean using an oily rag. Solvents like aceton or petroleum ether can be used to clean the equipment. However, here you must make sure that the adhesive foil on the underside does not come off by acci dent. After cleaning with solvents the iron components should be prepared with a thin layer of anti-corrosion oil. This device should be stored in a dry location.

Any iron shavings adhering to the magnets can be removed with adhesive tape.

1

IBS-Magnet, company brochure, ww.ibsmagnet.de 3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com Subject to technical amendments © Copyright 2015 3B Scientific GmbH

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