SCIENCE EXAM

Seite 1

Magnets as compasses -

The needle part of the compass is a magnet and magnets have a north and a south pole like that of a compass.

Where and why compasses point in the direction they do - They follow the lines of the magnetic field.

Types of electric current

- Alternating current and direct current

AC - Alternating current is where the electric current changes direction continually and an example is a fridge (anything that comes from the wall) WE energy supplies us with alternating current.

DC - Direct current is electric current that flows in only one direction an example is a battery.

Magnetic poles - North and south. North pole is located in Canada (80 degrees N latitude) and is actually the magnetic south. The south pole is near Australia and is at (80 degrees S) It is where the magnetic field enters the earth and where it is strongest.

The Earth's magnetic field - magnetosphere. It is becoming more weak. Magnetic field reversals are supposed to happen every 300,00 years. But the last one was about 750,000. Protects us from solar radiation. Strongest at the poles because it is where the lines converge.

Aurora's - names / what causes them / where are they seen

Aurora Borealis is in Canada. Aurora Australiais is in Australia. The cause is solor winds. The sun releases charged particles called solar winds and they collide with the Earth's magnetosphere and they attach onto the lines of the magnetic field and they travel to the poles. WHen they enter the poles they react with the atmosphere and the energy is released in the form of light.

Make magnetic field of magnet visible - Put a bar magnet down and sprinkle iron filings around it. The iron fillings will align themselves along the magnetosphere.

What creates magnetic fields - THEORIES

The Earth spins which causes convection currents in the liquid outer core. This creates an electric current which then passes through the solid inner core (made of magnetic materials) when it passes through it causes a magnetic field to form

CONS - doesn't explain why or how the magnetic field reversals occur. and does not explain why the magnetic field is getting weaker bc the earth just doesn't randomly stop spinning or change direction.

THE HOT INNER CORER HEATS UP THE OUTERCORE. This causes convection currents in the liquid outer core. And the movement in the outer core causes an electric current which passes through the inner core and causes a magnetic field.

CONS - The convection currents would stop happening because of the lid (the crust on the beaker)

PROS - it explains other things as well ex - tectonic plate movements. The theory could still work bc there are holes in the crust (volcanoes)

What is the cause of magnetism?

-The atoms are lined up and therefore the valence electrons spin in the same direction. Other metals are added (paramagnetic things) to the magnets to make them stronger and keeps the atoms lined up.

Ferromagnetism -

Iron, Nickel, Cobalt and, Gadolinium. Magnetization

Input Devices -

Keyboard, mouse, microphone, joy stick, touch screen, scanner, camera

Output Device -

Speakers, projectors, monitors, printers, laser printers, plotter

CPU and its functions -

Central Processing Unit the main microprocessor. The "brains" of the computer. All info goes through it.

CD/DVD

CD Record

CD RW re writeable

CD ROM

CD (650 - 700 MG)

DVD (7 GB)

ROM

Read Only Memory. Cannot be changed. Bios

(instructions on how to start up your computers. Without Bios the computer doesn't turn on) is here. Its there when the computers are shut down.

RAM

Random Access Memory.temporary/can be changed allows data to be accessed in any order

info is lost if power is shut down (unless saved)

STORAGE DEVICES floppy disk, flash drive, CD, DVD hard disk

COMPUTER PARTS AND WHAT THEY DO heat sink fan-primary source of cooling for computer CPU-brain of computer microprocessors-brains of computer power sources- supplies power to computer battery audio (idk if it audio port or slide) ethernet modem-transforms computers digital data to analog data for transmission over phone lines, then reconverts the data to digital video cables-connects drives to motherboard hard disk drive-reads/writes data to a hard disk, stores info

floppy disk drive-reads/writes floppy disks motherboard-main circuit board of computer. This connects and enables the operation of all components of the computer CD/DVD drive

network card-a circuit board used to connect the computer to a local are network (LAN) - memory than can be created or deleted over time, volatile ROM- memory that cannot be deleted, nonvolatile

ANALOG long, legato, continuous signal every sound is heard stylus/needle (usually)

DIGITAL short, staccato, separate signal better sound quality signal comes so fast that you can't hear the spaces in between

BINARY made up of 2 digits- 1,0 1-pit 0-land Computers process digital data in the form of a pattern of electric pulses

SEMICONDUCTORS -substance that conducts electricity better than a insulator but not al well as a conductor -nonmetals semiconductors conduct electric current based on how its electrons are arranged -when atoms bond, share VE, no electrons free to make electric current (but conductivity can be changed)

ELECTRONIC COMPONENTS AND THEIR USES/FUNCTIONS IN DEVICES

diode-electronic component that allows electric charge to move mainly in one direction (controls direction of current) -LED light instead of heat -help change AC to DC when 2 layers in a diode meet, the "extra" electrons from n-type move to fill in holes in p-type this gives n-type a positive charge and p-type a negative charge. Diode is connected to source of energy so that positive terminal is closer to the p-type layer a current is made if the connections are switched = no current

transistors- amplifies/increases current; used in amplifiers, oscillators, and switched

DOPING the addition of an impurity to a SC -adding impurity changes arrangement of electrons some atoms of a SC are replaced by some atoms of another element that has a different # of electrons

N-TYPE extra electron

P-TYPE hole

INTEGRATED CIRCUITS circuit whose components are formed on a single semicondictor -helped shrink things (transistors did too) -alse made things faster since everything is small: replaced wires

WHAT DOES IDE ENDING MEAN negative charge

CHARGED ATOMS ARE CALLED ___________ ions

TYPES OF CHEMICAL BONDS covalent- share electrons ionic-transfer electrons -the VE bond -they are transferred or shared

WHERE ARE ELECTRONS FOUND

orbiting around the nucleus

HOW TO FIND VALENCE ELECTRONS

Switch the subscripts

PROPERTIES OF NOBLE GASES unreactive

gases

complete valence shell

HOW TO DETERMINE HOW MANY ATOMS OF AN ELEMENT ARE IN A COMPOUND

Counting the subscripts

DIATOMIC ATOMS

7 of them

oxygen, hydrogen, nitrogen, bromine, iodine, fluorine, chlorine

LAW OF CONSERVATION OF MASS

Matter / ENGERGY can neither created nor destroyed so therefore the mass of the reactants is the same as the mass of the products.

New Page