Magnet: an object that attracts certain metals, mainly iron The property of magnets to attract metal is called magnetism Magnets do not attract all metals. They don’t attract materials such as wood or rubber. Magnetism is a force. The space in which a magnet’s force can act is called its magnetic field. Each magnet has two magnetic poles where the magnet’s force is the greatest.
Magnetic Poles: the 2 areas on a magnet with the greatest magnetic force When a bar magnet can swing freely, one end always points North. magnetic poles like – repels unlike - attracts
The Earth as a magnet The center of the Earth is made up mostly of melted iron. As Earth spins, the iron particles line up. Imagine Earth with a giant bar magnet inside. This means that Earth has a magnetic force field around it. The needle of a magnetic compass is a permanent magnet. The needle can always turn freely. One end of a compass needle always turns to find north. Who is a compass helpful for? sailors
Magnetism and electricity can produce energy of motion. Electromagnet: a strong temporary magnet that uses electricity to produce magnetism Examples: blender doorbell
Motor: a device that changes electrical energy into energy of motion Generator: a device that uses magnetism to convert energy of motion into electrical energy. Uses energy all the time: fridge clock DVD player computer Uses energy some of the time: fan washing machine
Essential Question: How is an electromagnet different from a bar magnet? 1) Magnetic force can be controlled. 2) can be turned on and off
Study Guide 1.An conductor is a material that electric charges can flow through easily. 2.The pathway that an electric current follows is called a(n) electric circuit. 3.The force of a magnet is strongest at the magnetic poles. 4.A motor is a device that uses magnetism to convert electrical energy into energy of motion. (mechanical) 5.An electric cell is a device that changes chemical energy into electrical energy. 6.Objects with unlike electric charges attract. Like items repel. 7.Static electricity is built-up electric charge.
8.Open circuit: gap, or opening, in a circuit 9.Closed circuit: connect wire, battery, & bulb without gaps 10.Series circuit: current passes each part in a single pathway 11.Parallel circuit: current passes in >1 pathway 12.Name 3 conductors: copper, silver, water, living things 13.Name 2 insulators: plastic, rubber 14.In a string of lights, all of the lights do not work if one bulb is removed. This is a series circuit.
What is static electricity? What causes static electricity to discharge? Static electricity is a build-up of negative electric charges. This build-up will remain until these negative charges jump from a charged object to another object. This “jump” creates the shock you feel. You rub a balloon with a wool cloth, and touch it to the wall. The balloon sticks. What can you conclude about the electric charges on the balloon and on the wall? The balloon receives negative charges from the wool cloth. The wall is neutral object that contains positive charges. These unlike items attract.