MAGNETISM.

MAGNETISM.

BAR MAGNETS
1. bar magnets are permanent magnets
2. Magnets are made from magnetic materials. These are metals that can be magnetised or will be attracted to a magnet. Most materials are not magnetic, but iron, cobalt and nickel are magnetic. Steel is mostly iron, so steel is magnetic too.
ELECTROMAGNETS
1. When an electric current flows in a wire it creates a magnetic field around the wire. By winding the wire into a coil we can strengthen the magnetic field. Electromagnets are made from coils like this.
  1. REMEMBERED FACTS:electromagnetic fields are created when an electric wire is wrapped around an magnetic source. We can make it stronger by wrapping the wire around the magnet in a coil.
2. We can make an electromagnet stronger by doing these things: wrapping the coil around an iron core adding more turns to the coil increasing the current flowing through the coil.
3. The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by turning the battery around. Unlike bar magnets, which are permanent magnets, the magnetism of electromagnets can be turned on and off just by closing or opening the switch.
  1. REMEMBERED FACTS: electromagnets have the same magnetic fields as bar magnets, except that they can be reversed and turned off.
MAGNETIC FIELDS
1. They fill the space around a magnet where the magnetic forces work, where they can attract or repel magnetic materials.
2. CANNOT BE SEEN.
3. Although we cannot see magnetic fields, we can detect them using iron filings. The tiny pieces of iron line up in a magnetic field.
  1. REMEMBERED FACTS: magnetic fields cannot be seen so we use iron filings to detect where they are. Iron filings can attract or repel magnets. The magnetic field lines flow from north to south, they are more concentrated at the poles.
4. the field lines have arrows on them the field lines come out of N and go into S the field lines are more concentrated at the poles.
ELECTROSIS
1. Electrical energy can cause chemical reactions. This happens in a chemical process called electrolysis.
2. http://www.bbc.co.uk/bitesize/ks3/science/images/electrolysis.gif
3. 1 Pieces of metal, called electrodes, are placed in the water. 2 A little sulphuric acid is added to the water to make the process work. 3 The electrodes are connected to a battery. 4 The water completes the circuit between the electrodes and current flows
4. Where the electrodes come into contact with the water chemical changes take place, producing bubbles of gas. Oxygen at one electrode and hydrogen at the other one. This electrolysis produces twice as much hydrogen as oxygen. They are both useful gases used in many chemical processes in industry.
  1. REMEMBERED INFORMATION: electrosis is a chemical reaction caused by an electrical current touching water. When water touches the electrical circuit, it creates a chemical reaction where the electrodes and water mix, causing oxygen to appear at one electrode, and hydrogen at the other. Twice as much hydrogen is created the oxygen.

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