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56 Cards in this Set
- Front
- Back
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What are magnets composed of? |
Magnetic substances eg. Cobalt (Co), nickel (Ni) and Iron (Fe) |
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What are the two types of magnets? |
Electromagnets and permanent magnets |
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What does a permanent magnet have and where is the attraction? |
- North and south pole; with most attraction occuring at the poles - forns permanent net magnetic fieldl |
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What will happen to the poles of a magnet if you split it in half? |
The smaller pieces of magnet will have their own poles |
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What are the two rules of magnetism? |
1. Like poles repel against each other 2. Unlike poles attract |
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What do magnetised materials produce? |
Magnetic fiels that exerts force on other objects placed in the field |
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What is the cause of magnetic fields? |
Motion of electrons around the nucleus; causing a single atom to be a small magnet with its own field |
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What occurs in non-magnetic materials? |
The materials direct the mini fields in many directions; cancelling each other out |
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How does constructive superposition occur? |
When the mini fields line up against each other in same direction |
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What is the group of atoms that cause magnetic fields in the same direcrion called? |
Magnetic domain (FOUND IN FERROMAGNETIC) |
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What is the space around a magnet called? |
Magnetic field |
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What are magnetic field lines? |
- Filings that form lines between north and south pole - direction of lines will be in the direction of a compass needle in the field - closer the lines; strobger the field - lines never touch each other |
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How will field lines be drawn? |
From north to south |
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Identify how field lines between 2 magnets will look like |
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What occurs when two like poles face each other? |
A point where no field lines occur and no force exherts on another object |
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What occurs to an iron piece held to a magnet? |
It also becomes magnetic but has opposite pole; forming an attraction between the iron and magnet |
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Describe the earths core |
- It is composed of nickel and iron that creates a magnetic field - field lines of core create north and south pole where forces are strongest |
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Are north and south poles of earth same as geographical poles? |
NO. The sun determines geographical poles 6 months sun is above horizon and 6 months below |
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Why do magnetic poles differ? |
As a result of changing magnetic fields of earth Compass of north = south pole of magnetic and vice versa |
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What is the name of the angle between the geographical pole and magnetic pole? |
Angle of declination |
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What is the purpose of the magnetic field? |
- protect from dangerous radiation from the solar wind (charged particles of sun that blows) blows) |
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Describe how the magnetic field protects us from solar wind |
- The wind is reflected away from earth - some light moves along field in south and north pole and into the atmosphere; causing it to glow and form aurora borealis |
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What happens if the sun erupts and sends out more molar wind than normal? |
It causes the magnetic field to disort and move; causing damage to some elsctrical equipment |
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Name four uses of magnetism in the modern world |
- computer discs to store info - electric motors - satellites - navigation of ships and migrating animals from one hemisphere to other |
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Identify iron fillings between to opposite poles of magnets |
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Identify iron fillings between to repulsive poles of magnets |
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How does the magnetic field lines move across oppositly charged poles? |
The field lines will move from north to south pole |
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What will occur to the field lines in like poles? |
The field lines will bend away from each other when they come near to eaxh other |
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What is static elecetricity? |
It is the study of sationary charges as a result of the formation of charges in the suface of an object |
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What does a neutral atom have? |
Same amount of protons and elecrons |
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What type of materials do we get? |
Positvly charged and negativly charged materials (positive occurs when they lose electrons and negative happens when they gain) |
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Give the law of conservation of charge? |
Charge cannnot be created not destroyed but can only be transferred from one object to the other |
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Give an example of two materials that will attract and repel |
1. Two glass rods with one rubbed with asbestos & other with silk cloth 2. Two glass rods that are both rubbed with silk cloth |
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Describe neutral or no charges between a material |
Neutral - no charge and no force between materials |
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What is polarisation? |
The process where a redestribution of electrons in a neutral object takes place so it is a dipole molecule |
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What is polarisation? |
The process where a redestribution of electrons in a neutral object takes place so it is a dipole molecule |
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What occurs if a charged object is brought close to a neutral one? |
It will attract electrons of neutral if charged object is positive It will repel electrons of neutral object if chaged one is negative |
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When does polarisation occur? |
When electrons are free to move; such as in metals |
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How will polarisation occur in dipole molecules? |
The molecules will rotate so that the oppositely charged molecule side faces the charged object |
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Describe the purpose of an electroscope? |
1. It shows the distribution of electrons 2 It is an apparatus which shows if an object is charged |
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What occurs when a charged object is brought to an uncharged electroscope? |
The neutral electroscope changes into a positively charged cap and copper condeuctor and negativly charged leaves (leaves seperate) |
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How else can redistribution of electrons to polarize an object occur? |
If you have two neutral objects close to one another |
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What is a way to charge objects? |
By Tribo-electric charging (friction) Induction |
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How does induction occur? |
When an object is charged without the other object charging it |
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Describe the process of changing a neutral sphere by induction |
A balloon with a negative charge (close but not touching) will repel the electrons of the neutral sphere. When a person 'grounds' the electrons (sends it to the ground), the sphere will mostly have protons. This gives it a positive charge |
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What is the: - unit of charge - symbol for charge - charge of electron |
1. Unit is coulomb (C) 2. Symbol is Q 3. Charge is -1.6 × 10^-19 C |
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What will occur if a charged object of -12 C touches a neutral object? |
The charge will distribute evenly so that both objects have a charge of -6 C. THEY WILL THEN REPEL EACH OTHER |
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If sphere A has a charge of -6 C and sphere B a charge of +2, what will occur? |
The spheres will attract each other; distribute themselves evenly and then repel each other |
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How do you determine the new charge of a sphere with B -6 C and a sphere with A +2 charge? |
1. You add the original charges together 2. Then divide the answer by two 3. The answer is - 2 C |
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What are conductors? |
Materials that allow electrons to flow through them. They conduct electricty insulators are the opposite of this |
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What non metallic substances conduct electricity? |
Acid, water and carbon |
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What are 3 uses of charge in todays world? |
- the spray paint of vehicles - printers of computers - photocopiers - lightning |
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How does lightning occur? |
Occurs when there is a very big potential difference beteeen the clouds and the ground |
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Describe the process in which lightning strikes |
1. Top of cloud becomes positive charged and bottom negative (in an electric storm) 2. Negative charge at bottom cloud repels negative charge of earth; causing earth to be positive 3. Thus, a strong attraction occurs and an invisible ray of electrons move toward earth |
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Apart from two unlike poles of rods being attracted, what else is attracted? |
The material (used to charge the rod) will be attracted to the rod |
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What indicates strong magnetic field? |
Close magmwtic field lines and density of field lines also indicate this. |
