Science Chapter 9 Flashcards
Ace Science
What do Magnets attract?
Magnets attract object made of magnetic materials
What are some examples of magnetic materials?
Iron, Nickel and Cobalt, alloys, stainless steel
What object are made of stainless steels
Spoons,Fork and Knife
What are Permanent magnets made of
Magnetically Hard materials such as steel
What function does Permanent magnets have
They retain their magnetisation once magnetised
What are an example of Magnetically soft material
Iron
What are the disadvantage of Magnetically soft material
they lose their magnetisation easily.
What is the advantage for magnetically soft materials
They are suitable for temporary magnets such as electromagnets
What are Magnetic Poles
Magnetic Poles are the parts of a magnet that exert the greatest force.
What do Magnetic poles occur in
pairs called North(N) and South(S)
Why poles are called north and south
A magnet suspended so that it can rotate freely and horizontally will eventually settle down with one pole facing north and the other facing south
The pole is therefore called the ‘north seeking pole’
What colour is north
blue
What colour is south
red
What does alike poles react
They repel
What does unlike poles react
They attract
What is the direction of North Poles
Out
What is the direction of South Poles
In
What is Magnetic Field
Magnetic field is a volume of space where magnetic force is exerted
All magnets are surrounded by magnetic fields.
True or Flase
True
How can the shape of a magnetic field be shown
iron fillings or plotting compases
State all the uses of electromagnets
-Scrap yard crane
Explain how electromagnets work
The iron core of the electromagnet is a soft magnetic material.
When current flows the iron becomes strongly magnetised and so picks up the scrap iron and steel.
When the current is turned off, iron loses its magnetisation and so releases the scrap.
What are Earth’s magnetic field caused by
electric currents flowing through the molten outer core of the Earth
What shape is similiar to the magnetic field
around a bar magnet
What is the origin of Earth’s Magnetic Field
The spinning of the metalic Inner core and convection currents in the metalic outer core creates a magnetic field around the earth
How can magnetism be induced in a magnetic material
If the magnetic material is placed within a magnetic field.
What if the magnetically hard material is removed from the field
It will retain its magnetism
What is Lodestone
a rock in Earth’s crust
What does electromagnets consists of
IT consists of a current carrying coil wrapped around an iron coil
How do electromagnets differ from normal magnets
They are made by passing an electric current through a wire that has been wrapped around iron. The current creates a magnetic field and magnetises the iron core.
When the current is turned off, the iron loses its magnetism.
What do magnetic materials include?
Metals iron nickel and cobalt
What are permanent magnets
Magnets with magnetic field that are always there, you cannot switch it on and off
How is an electromagnet made
wrapping a wire around a magnetic material, such as iron. The wire that is wrapped around is called a COIL. Material in the middle of the coil is called the CORE
How to find out which pole is it of an electromagnet
- Use a magnetic compass that points along magnetic line field, it will point toward the south pole
- Use a bar magnet with known poles. To attract unlike poles and repel like poles. With this you can bring bar magnet to electromagnet detect which pole is which
Give examples of applications of electromagnet
-Fire door,held with an electromagnet. Fire alarm switched on, the magnet is switched off and door closes
-Toaster, the handle is pushed down, an electromagnet holds down a metal basket with bread in it. A timer turns the electromagnet off and the metal basket pops up with toast.
3 things that are needed to make an electromagnet
-a coil of wire
- a magnetic core inside the coil
- an electric current flowing in the coil
factors that will affect the strength of an electromagnet
-more turns in the coil, the stronger the electromagnet
- material of the core. Iron and some types of steel in the core make the strongest electromagnets
- current in coil, the greater the current the stronger the electromagnet
What should you do when increasing the number of turns on the coil
Keep the current and core the same
What should you do when using more cells to increase the current.
Keep the number of turns on the coil and core the same
What should you do when using a soft iron core in place of a steel core
Keep the number of turns on the coil and the current the same
Suggest two changes to the electromagnet that would make the pointed end of the nail become the south pole(originally north pole)
- Reversing the direction of the current
- Turn the pointed nail around towards the other direction.
