Q:I want to know what chemical(s) and materials makes up a magnetic sand?

yes, iron minerals. mostly Magnetite which is iron oxide, and Pyrrhotite which is iron sulfide. the exact composition of magnetic sand depends on the source rock that was eroded.

Q:Barkhausen effect in different magnetic materials of different size why sound

The permalloy film (is the moment not fat loop of ferromagnetic material) into a coil, the permanent magnet N pole to coil and along the coil axis, youyuanerjin permalloy films will be magnetized, the rustle of the horn. If the permanent magnet moves very slowly, the speaker makes a noise. When the permanent magnet does not move, the noise stops immediately and continues to move forward. The horn makes a noise again, and the nearer it gets, the louder it becomes. When the permanent magnet leaves the coil slowly, the horn also makes a noise, but smaller than the magnetization (this is because there is a reversible process in the irreversible process. If it is a good rectangular hysteresis loop material, there is no such phenomenon. The farther the permanent magnet goes, the smaller the sound, until there is no noise. The direction of the magnetic poles unchanged, then moved closer to the permanent magnet coil, permalloy film was again

Q:difference between magnetic hard drives and magnetic tape drives?

Tape Drives Vs Hard Drives

Q:So may book says The direction of any magnetic induction effect is such as to oppose the cause of the effect. I have read many internet fora and posts but I could‘nt understand Lenz‘s law in simple English.And the right hand rule too. Where should I point my thumb or my fingers about to curl? Thanks

Lenz's Law explains the direction of induction in a magnetic material. Electromagnetic induction may occur due to changing magnetic field, changing dimensions of material or both of them. Now, in any of the above case(s), an induced e.m.f. is generated, The induced e.m.f. so produced is directed such that it opposes the effect the producing it. It can be considered to be some kind of an electrical inertia. Suppose a disk is falling through an upward non uniform magnetic field which is increasing as it goes further down. This causes induced e.m.f. in the disk. Now the direction of the induced e.m.f. will be such that it opposes the original magnetic field, i.e.- tries to decrease the external magnetic field. So, its direction will be directed downwards. Now, to find direction of current, RIGHT HAND THUMB RULE is used. It states that the curl of fingers and the thumb represent the direction of current and the direction of magnetic field produced, not respectively though. If your fingers curl along the current, the thumb will point along the field, and vice versa. It's upto you to decide whichever is suitable. This rule thus proves that Current and Induced magnetic field are normal to each other. In the above example, the current flow will be CLOCKWISE.

Q:What metals are not attracted by magnets, please?

Experiments show that any substance can be magnetized more or less in an external magnetic field, but only in varying degrees of magnetization. According to the characteristics of a substance in an external magnetic field, substances can be roughly divided into three classes: paramagnetic, diamagnetic, ferromagnetic.

Q:when they invented the compass. Cos according to my knowledge magnetism and it‘s connection to the north and south poles are a European discovery. So, what led to the Chinese inventing the compass or was it an accidental discovery?

I think it just an accidental discovery. The ancient Chines believe that the sky is round and the earth is square, and China live in the central of world arounding by sea. And that's why they named their county as 中国(central state). There is little modern geography in ancient China at all.

Q:How can a strong magnet be drawn apart?

Powerful magnets are pulled together to separate the effective method of magnetic separation: only the material that can be adsorbed on the magnet can play the role of blocking the magnetic field, and the thicker the material, the better the effect of the magnetic separation.

Q:1.- how a compass needle moves when it is placed in a magnetic field????2.- why only certain materials are magnetic?3.-how heating a bar magnet would change its magnetic fiel?PLEASEE

The compass needle is rotated so that it becomes parallel with the magnetic field of Earth. This happens because of the magnetic moment of the magnet's atoms, and this way magnet reaches the lowest energy level. The materials have magnetic properties which are determined by the magnetic moment of their atoms, that depends on the atomic mass and hence the shape of the atom. If you imagine (a very simplified model) that each atom contains electrons spinning around the nucleus and around themselves, they form microscopic electric currents microscopic magnetic fields (Electrodynamics explain how is produced a magnetic field from a non-stable current). The field produced by each electron adds up, as each atom's field has the same direction, and we have a magnetic material. The atoms in a magnet have fixed positions, that are determined by the lowest internal energy of the material. If the magnet is heated, it's atoms gain extra energy and start moving faster and more freely. In this way the initial structure is destroyed, and when the material is cooled again its magnetic field can be found different or completely destroyed.

Q:I‘m not gonna bring it on as carry on but in my luggage

Well, if it's only for three days I really don't think you NEED a flat iron. Bring it if you want though. Bring: Swimmers. Towels Water shoes ( if it's a public lake there might be sharps on the bottom) TORCHES. Nothing is scarier than getting lost near a lake at night Shampoo and conditioner. Hope this helps

Q:is there a material (on earth,or in space) that is attracted to earths magnetic field, such as a metal pellet to a magnet

the sphere is equivalent to that of a bar magnet, yet this similarity is superficial. The magnetic field of a bar magnet, or the different style of everlasting magnet, is created by skill of the coordinated spins of electrons and nuclei interior of iron atoms. The Earth's middle, besides the undeniable fact that, is warmer than 1043 ok, the Curie factor temperature at which the orientations of spins interior of iron replace into randomized. Such randomization motives the substance to lose its magnetic field. as a result the Earth's magnetic field is brought about no longer by skill of magnetized iron deposits, yet regularly by skill of electric currents interior the liquid outer middle (because it spins, electrons tend to stay in the back of, subsequently generating a small cutting-edge). yet another characteristic that distinguishes the Earth magnetically from a bar magnet is its magnetosphere. At super distances from the planet, this dominates the exterior magnetic field. electric currents precipitated interior the ionosphere additionally generate magnetic fields. this type of field is often generated close to the place the ambience is closest to the sunlight, inflicting daily differences that may deflect floor magnetic fields by skill of as much as a minimum of one degree.