UNIT 9. Energy, electricity and magnetism

THE TEST WILL BE 6TH APRIL 2022

ELECTRICITY 

STATIC ELECTRICITY: is a charge that objects can receive under certain conditions such as: 

• Combing hair with a plastic comb
• Rubbing a glass o plastic object with a wool cloth.

 These objects become electrically charged and they can become positively or negatively charged. 

Objects that have opposite charges(positive and negative) attract each other.

 Objects that have the same charge repel each other.

ELECTRICAL CURRENTS 

Electrical currents are the transfer o fan electrical charge through objects. They can only be transferred if each of the objects has an opposite electrical charge. Form example: 

• Storm clouds and the Surface of the Earth have opposite electrical charges, this is lightning
• A battery has a negative pole and a positive pole, so when they are connected with a cable, the charge moves from one pole to the other.

ELECTRICAL ENERGY can produce changes in matter and can be transformed into another type of energy.

 MATERIALS AND ELECTRICAL CURRENTS 

To produce an electrical current a charge must be able to move from one object to another and this is only posible if the charge is travelling along a material that allows it to move.

 MATERIALS: 

• CONDUCTIVE MATERIALS: are materials that allow an electrical current to pass through it. Examples: metals(copper),  graphite or salt water.
• INSULATING MATERIALS: are materials that doesn´t allow an electrical current to pass through it. Examples: Wood, plastic or rubber.

  ELECTRICAL CIRCUIT An electrical circuit is a group of elements that allow an  electric current to Flow. 

COMPONENTS OF A CIRCUIT: 

• Generators: transform different types of energy into electrical energy and produce an electrical current. Examples: batteries, alternators or solar panels.
• Conducting cables: transport an electrical current from the generator to the receptor. They are usually covered in an insulating material.
• Switches: are used to turn an electrical current on and off.
• Receptors: use the electrical energy that has been transported to them by the cable. Examples: lightbulbs, ovens…

MAGNETISM

Magnetism is the property that allows to attract or repel objects.

CHARACTERISTICS

Magnetite is a natural mineral with magnetic properties. There are some other artificial magnets such as iron, cobalt nikel and neodyium.

All magnets have opposite poles and generate a magnetic field.

Poles of a magnet: are two áreas that normally at are the end of the magnet. The poles are called north and south.

 Opposite poles attract

Like poles repel each other.

Magnetic fields: are the influence magnets have on the space around them.

The Earth´s magetism

At the centre of the Earth is a mixture of metals (iron, nikel..) that have magnetic properties. Beacuse of this, the Earth acts like a giant magnets. It has got a magnetic north pole a magnetic south pole which creates a magnetic field.

The uses of magnetism

Compasses: contain a small magnetic needle that detects the Earth´s  magnetic field and allows us to find the north and south.

Storing information: certain electrical equipments(computers, memory sticks… contain materials that have magnetic properties to store information.

 Other applications:locks, suitcases, bags, fridge doors… use magnets to keep them closed. Also to hold thing in place.

ELECTROMAGNETISM is the use of electricity and magnetism. 

ELECTROMAGNETS are when we turn iron bars into magnets. 

ELECTROMAGNETIC GENERATORS use magnetism to generate electricity.